49 



^LABORATORY STUDY °I 
HOUSEHOLD CHEMISTRY 



JONES 



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WM 



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Book t s/ jL 

Copyright N° 

COFXRIGiST DEPOSFT. 



A LABORATORY STUDY 

OF 

HOUSEHOLD CHEMISTRY 



BY 

MARY ETHEL JONES 

FORMER TEACHER OF CHEMISTRY IN THE 
LOS ANGELES HIGH SCHOOL 



>XK< 



ALLYN and BACON 

BOSTON NEW YORK CHICAGO 

ATLANTA SAN FRANCISCO 



-ft*** 

51 



COP /RIGHT, 192i, 

BY MARY E. JONES 



SEP 24 '2 



NorinooB Press 

J. S. Cushing Co. —Berwick & Smith Co 

Norwood, Mass., U.S.A. 



©C1.A627093 



PREFACE 

These experiments in Household Chemistry are arranged 
to meet the demand for work in chemistry for girls. They form 
a practical course in the chemistry of the household and of 
common things, and are helpful both to pupils who do not go to 
college and to those who do. 

Above all, the course u practical. While the fundamental 
principles of chemistry are as thoroughly emphasized in the first 
half year of this course as they are in any course in general chem- 
istry, the experiments that illustrate them are made as prac- 
tical as possible. 

The last half of the course is largely organic chemistry made as 
simple as possible and used so far as possible in the study of fuels 
and illuminants, food principles, food substitutes, textiles, soaps, 
laundering, bleaching, blueing, dyeing, and leavening agents. 

All of the experiments and the wording of the directions have 
been tried for five years by different teachers with classes of 
girls. Additions and changes have been made each term until 
the manual satisfies all the requirements of the course. 

Many teachers have assisted in the preparation of this work. 
The author wishes particularly to express her indebtedness to 
Miss J. Maud Blanchard, her first teacher in chemistry, to Miss 
May Kimble and Mr. J. H. Hanna, both of the Los Angeles 
High School, and to Mr. C. W. Sandifur, of the Hollywood High 
School. 

Mary Ethel Jones 

Los Angeles, California 
April, 1921 

iii 



CONTENTS 



Part I. First Term's Work 



I Preliminary Experiments 

Experiment 1. The Bunsen Burner .... 
Experiment 2. The Units of Length, Volume, and 

Weight Used in Chemistry ..... 

Experiment 3. How to Make Simple Apparatus from 

Glass Tubing 

Experiment 4. Physical and Chemical Changes . 
Experiment 5. Elements, Compounds, Mixtures . 

II Oxygen and Hydrogen 



PAGE 

2 



Experiment 6. 
Experiment 7. 
Experiment 8. 

Burns 
Experiment 9. 

drogen 
Experiment 10. 

drogen 



Ways of Freeing and Collecting Oxygen 
Preparation and Properties of Oxygen 
What Takes Place When a Substance 

Preparation and Properties of Hy- 

Two Other Methods of Preparing Hy- 



III 



IV 



Water 

Experiment 11. 
Experiment 12. 
Experiment 13. 
Experiment 14. 

Water 
Experiment 15. 
Experiment 16. 

Nitrogen and the Air 
Experiment 17. 

gen . 
Experiment 18. 
Experiment 19. 



The Synthesis of Water 

How to Test Hydrogen and Water 

The Solvent Power of Water 

Boiling Point and Freezing Point of 

How to Purify Water 
Properties of Hydrogen Peroxide 

Preparation and Properties of Nitro- 

The Composition of the Air 
Ammonia, NH 3 ..... 



12 
14 

17 

19 

22 



24 
25 

28 

30 
32 
34 



35 
37 
40 



Vi CONTENTS 

V Acids, Bases, and Salts page 

Experiment 20. General Properties of Acids, Bases, 
and Salts 41 

Experiment 21. Methods of Forming Acids, Hy- 
droxides, and Salts 45 

Experiment 22. Solutions That Conduct the Electric 
Current 49 

VI The Halogens and Hydrochloric Acid 

Experiment 23. Chlorine, Bromine, and Iodine . . 52 
Experiment 24. Preparation and Properties of Hydro- 
chloric Acid, HC1 54 

VII Sulfur and Compounds of Sulfur 

Experiment 25. Sulfur and Compounds of Sulfur . 55 
Experiment 26. Sulfuric Acid and Hydrogen Sulfide . 57 

VIII Carbon. Carbon Dioxide. Flames 

Experiment 27. Carbon 59 

Experiment 28. Carbon Dioxide, C0 2 .... 60 

Experiment 29. Carbonic Acid and Carbonates . . 62 

Experiment 30. Flames 63 

Part II. Second Term's Work 

IX Common Organic Compounds 

Experiment 31. Tests for Organic Compounds . . 67 

Experiment 32. Hydrocarbons 69 

Experiment 33. Some Common Alcohols ... 73 

Experiment 34. Properties and Uses of Some Common 

Organic Acids 76 

Experiment 35. Fuels and Illuminants ... 80 

X Chemistry of Foods 

Experiment 36. Water in Foods 83 

Experiment 37. Inorganic Salts in Foods (Mineral 

Matter or Ash) 84 

Experiment 38. Starch and Dextrin .... 86 

Experiment 39. Cellulose 88 

Experiment 40. Gums and Pectin .... 90 

Experiment 41. Sugars 93 

Experiment 42. Fats and Oils 96 



CONTENTS 



Vll 



Experiment 43. The Albumens and Casein 
Experiment 44. The Globulins and Albuminoids 



XI Digestion of Food 

Experiment 45. 
Experiment 46. 

XII Food Analysis 

Experiment 47. 
Experiment 48. 
Experiment 49. 

XIII Food Adulterants 

Experiment 50. 
Experiment 51. 
Experiment 52. 

XIV Food Values 

Experiment 53. 

XV Leavening Agents 

Experiment 54. 
Experiment 55. 

XVI Textiles 

Experiment 56. 
Experiment 57. 
Experiment 58. 
Experiment 59. 
Experiment 60. 



Digestion of Starch 
Digestion of Proteins 



Adulterants in Milk . 

Tests for Adulterants in Butter . 

Adulterants in Jellies and Candies 

Menu Making .... 

Products of Yeast Fermentation 
Baking Soda, Baking Powder 



Cotton, Linen, Wool, and Silk 
Textile Dyeing . 
Removing Spots and Stains 
Bleaching and Blueing 
Soaps, Cleansing Powders . 



Appendix 



PAGE 

99 
101 



103 
105 



Analysis of Milk . . . .108 

Babcock Test for Butter Fat in Milk 111 
Beverages — Tea, Coffee, Cocoa . 113 



The Metric System 

Temperatures ........ 

List of the Common Elements, Their Symbols, Atomic 
Weights and Valences ...... 

The Weight in Grams of One Liter of Various Gases 
Food Chemistry Outline . . . . 

Digestion of Foods ....... 

Action of Digestive Juicer 

Tables Showing Food Units Required Daily . 

Tables of 100 Food Units 

Special Solutions 169 



110 
US 
120 

122 

123 
125 

128 
130 
132 
135 
138 

141 
142 

143 
143 
144 
157 
158 
159 
161 



SUGGESTIONS TO TEACHERS 

As has been noted in the preface, this manual was not written 
to fit any particular textbook, but simply to outline a course in 
chemistry for girls. It has been found that any good up-to-date 
book in elementary chemistry can be used throughout the year's 
work. On the second term's work, however, it is well to give 
some reference work from the books mentioned. 

Most of the experiments can be performed in the double 
laboratory period of 90 minutes. Some of the experiments are 
short enough so that two experiments can be performed in one 
day. A few experiments require more than one double period. 

It has been our experience that a student will work to far 
better advantage in the laboratory if the instructor will spend 
five, or even ten, minutes at the beginning of the laboratory 
period discussing the experiment, emphasizing in particular the 
purpose of the experiment and the precautions to be observed. 
With a beginning class of girls, until they know something of 
laboratory technique, it is well to show just how the apparatus 
in the experiment is set up. 

The method of presenting the principles and just where and 
when to introduce the theories of chemistry to a beginning class 
of girls, varies with different teachers. There is an outline on 
food chemistry in the appendix that may be helpful to the 
students. 



IMPORTANT SUGGESTIONS TO STUDENTS 

1. Pay your laboratory fee. No student may be assigned 
a desk in a chemical laboratory until this fee is paid. Your in- 
structor will keep your receipt on file until you need it to present 
for refund. 

2. Provide yourself with the following : a rubber or oil- 
cloth apron, the standard laboratory notebook, some mop 
cloths, a cake of soap, one fourth of a cake of sapolio, and a 
sponge. 

3. If you break a piece of apparatus, make out a requisition 
slip for a new piece and replace it. 

4. Always keep your apparatus clean and your desk neat. 
Good chemists are never slovenly. 

5. Keep the sink in front of your desk clean. — Do not put 
acids or strong bases in it without flushing it well. Do not put 
matches, fats, oils, paper, pieces of sodium or potassium into the 
sink, but use the waste jars provided. 

6. Do not use more material than the amount specified. If 
too much is taken of either a solid or liquid, throw the excess into 
the waste jars ; never pour it back into the bottle. 

7. Never lay the stopper of a reagent bottle down on the 
shelf ; keep it in your hand and replace it when you are through. 

8. Never taste reagents unless told to do so. 

9. In case of accident see instructions on page xv ; if serious, 
report to instructor. 

10. Your notebook should be an honest record of your own 
observations and conclusions. 

xi 



SAFETY RULES 

1. Before a new experiment is begun at least ten minutes should 

be spent in the lecture room : 

a. To emphasize precautions to be observed in order that 

the experiment may be absolutely safe. 

b. To make clear the purpose of the experiment. 

c. To make the method clear. 

2. Experiments missed by a student are not to be made up in 

the laboratory unless carefully supervised by the instruc- 
tor. 

3. Have no materials on the distributing shelves except the 

materials for the experiment of the day. 

4. All other supplies should be kept in the storeroom and the 

storeroom kept locked. 

5. Poisons and materials not safe in the hands of students such 

as potassium cyanide, phosphorus (yellow), sodium, 
potassium, carbolic acid, and mercury salts, should be 
locked in a special cupboard. 

6. In the preparation of oxygen be sure that the manganese 

dioxide is free from carbon before it is mixed with the 
potassium chlorate. The teacher should perform the 
experiment in front of the class before allowing them to 
do it. 

7. Such substances as potassium chlorate, phosphorus, sodium, 

potassium ammonium nitrite, concentrated sulfuric acid, 
and concentrated nitric acids are not safe in the hands of 
the students in the crowded classes of the High School. 
Experiments involving the use of these substances should 
be performed by the instructor, 
xiii 



XIV SAFETY RULES 

8. Other experiments in which poisonous gases are prepared, 

such as chlorine, bromine, or phosphine, should be per' 
formed by the teacher. 

9. Unless the class is so small that the teacher can personally 

direct each student, the experiment on the preparation 
of hydrogen by any method should be performed b}^ the 
teacher. 

10. All experiments involving reductions by means of hydrogen 

or the burning of hydrogen should be performed by the 
teacher. 

11. Keep your first-aid closet well stocked. 

12. Carry all acid bottles with both hands, one on the bottom, 

one holding the neck. Carry one bottle at a time. 



LABORATORY FIRST AID 

1. Accidents, if serious, should be reported to the instructor. 

2. Cuts. Wash in running water, then with a piece of absorbent 

cotton saturated with iodine solution. Bandage to prevent 
contamination. 

3. Burns caused by hot objects. Cover with a paste made by mixing 

sodium bicarbonate and carron oil (equal parts of olive oil and 
lime-water). Then cover with cotton and bandage. 

4. $urns caused by acids. Wash with water, apply a solution of 

sodium bicarbonate, then treat as in 2. 

5. Burns caused by alkalies. Wash with boric acid, then treat as in 2. 

G. Acids in eyes. Wash with water, then dilute solution of sodium 
bicarbonate, then olive oil. Do not rub. 

7. Bases in eyes. Wash with water, then boric acid solution, then 

oil. Do not rub. 

8. Other substances in eyes. Use water, boric acid, then oil. Do 

not rub. 

9. If a chemical is swallowed call a physician. Meanwhile, give 

emetic of mustard and warm water. Consult " First Aid " for 
antidote. 

10. If irritating gases are inhaled — breathe fresh air. In case of 
hydrogen chloride, sulphur dioxide, chlorine, or bromine, a very 
dilute solution of ammonium hydroxide sniffed into the nose 
often brings relief. If the gases are in the eyes, bathe with water 
and boric acid. If overcome by hydrogen sulfide, inhale chlorine 
gas (prepared quickly by treating powdered potassium chlorate 
in a beaker with a few drops of hydrochloric acid at a time). 



xv 



HOUSEHOLD CHEMISTRY 

PART I 

FIRST TERM'S WORK 
I. PRELIMINARY EXPERIMENTS 

Upon entering the laboratory, hang your coat upon the 
hooks provided, roll back your sleeves, put on your apron, and 
check your apparatus with the following list. If anything is 
missing or not in good condition, report to the instructor. After 
the first day, broken or lost apparatus will be charged to your 
account. 

APPARATUS LIST 

1 Asbestos mat $0.10 

1 Beaker, 150 cc 35 

1 Beaker, 250 cc 40 

1 Crucible, porcelain, #0 . . . . .35 

1 Clay triangle 05 

1 Cover for crucible, #0 15 

1 Delivery tube, rubber, 18" 25 

1 Elbow glass, 3" X 6" 05 

1 Elbow glass, 3" X 3" 05 

1 Evaporating dish, porcelain, 50 cc 30 

1 Forceps, steel, 5" 15 

1 Flask, Florence, 250 cc 25 

1 Funnel, short stem, 3" diameter 30 

4 Gas bottles, wide mouthed, each , N . . . .15 

4 Glass plates (cover glasses), each 10 

1 



2 PRELIMINARY EXPERIMENTS 

1 Graduate (measuring cylinder), 50 cc 75 

12 Gas testers, wooden splints 05 

1 Box matches, safety 

3 Rubber connectors (3" rubber tubing) 10 

1 Stirring rod 05 

1 Stopper, 1-hole, pure gum 10 

1 Stopper, 2-hole, pure gum 10 

1 Test tube, side neck, 8" XI" 20 

12 Test tubes, 6" X|" each 05 

1 Test tube, 8" XI" 10 

1 Test tube brush 15 

1 Test tube holder (bent wire) 15 

1 Thistle tube, straight stem (safety) 60 

2 Watch glasses, 2" 05 

1 Wire screen, 4" X 4" 10 

PERSONAL LIST 

Apron, cloths, sponge, soap, sapolio, paper. 
After checking your apparatus, fold and put away your apron 
and lock the drawer and locker. Keep your key. 



EXPERIMENT 1 

The Buns en Burner 

Apparatus. Bunsen burner, matches, beaker, test tube, test 
tube holder, wire screen. 

Note to student: When you enter the laboratory, put on your apron and 
begin the experiment at once. Work independently unless otherwise in- 
structed. Do not waste time. Unfinished experiments will have to be 
finished after school. Put your name, the date, the number of the experiment 
at the top of a page in your notebook and record carefully each observation 
as you work. Be sure to have the instructor sign your notes before you leave 
the laboratory. Always bring your laboratory notebook with you on recitation 
days in order that the experiment just performed may be discussed. 

Note to teacher : Much time will be saved if the parts of the Bunsen burner 
are briefly explained before the students enter the laboratory. Also show 
how to heat a liquid in a test tube and how to use a ring stand. 



THE BUN SEN BURNER 3 

A. The Parts of the Burner. 

The Bunsen burner is a form of apparatus used for the 
burning of gas. It is the usual source of heat in the labora- 
tory. The name " Bunsen " has been given to the burner 
because it was first made by the German scientist Bunsen. 
It consists of a base and a tube which has two round openings 
in its lower part, through which air enters. A small band, 
with corresponding openings, fits the lower part of the tube, 
and by turning this the holes in the tube may be kept open 
or closed. The gas enters by means of a rubber tubing 
through the base. It mixes with the air that enters the 
openings in the tube and is burned at the top of the tube. 

1 . Unscrew the tube of the burner and examine the parts. 
Draw each part and label it. Put it together again and light 
the gas. To do this light a match and hold it about two 
inches above the end of the tube, then turn on the gas. If 
a burner " strikes back " and burns at the base, shut off 
the gas and light again. The flame should not be more than 
four inches high at any time. 

2. Shut off the air by closing the holes at the base. What 
happens to the flame? Open the holes again and admit 
air. Which flame is best for laboratory work ? Why? Put 
one of your splints into the base of the blue flame and 
gradually raise it. What part of this flame is the 
hottest ? 

B. How to Heat Glass Apparatus in the Bunsen Flame. 

1. To heat ivater in a test tube. Half fill a test tube 
with water, wipe the surface dry. Place the test tube clamp 
about the top of the test tube, as directed by the instructor. 
Incline the tube away from your face, but not toward your 



4 PRELIMINARY EXPERIMENTS 

neighbor. Apply the heat near the top of the liquid. Move 
the tube about in the hottest part of the flame, so that it 
may be uniformly heated. When the water boils, pour it 
into the sink and put the tube away. 

2. To boil a beaker of water. Place a wire screen on the 
ring of your ring stand. Place the burner under the screen 
and adjust the ring so that the screen presses down about one 
inch of the flame. (Note the instructor's model.) Half 
fill the beaker with water, wipe the surface dry, and place 
it on the screen. If the beaker were heated without the 
screen, it would probably break. How does the screen 
prevent this ? 

C. Before Leaving the Laboratory. 

Wash your apparatus and put it away. Be sure to put 
away your screen. Put the burnt matches and other scraps 
into the jars. Wipe the desk top with a cloth. Clean up 
in this way after every experiment hereafter. Be sure to 
lock your drawer and locker. The instructor must sign your 
notes before you leave the laboratory. Bring these with 
you at the next recitation. 

EXPERIMENT 2 

The Units of Length, Volume, and Weight Used in Chemistry 

Reference. Appendix in this manual. 

Apparatus. A meter stick, a short metric ruler, flasks represent- 
ing 1 1., 500 cc, 250 cc, 100 cc, balance. 

Note to student: Take careful notes. Number and letter the paragraphs 
in your notes to correspond to the paragraphs in the manual. If you do not 
understand the directions, ask the instructor for help. Have your notes 
signed before leaving the laboratory. Bring the notes for discussion at the 
next recitation. 



THE UNITS OF LENGTH, VOLUME, AND WEIGHT 5 

A. Unit of Length. 

The unit of length most often used in chemistry is the 
centimeter. Examine a meter stick and notice that a meter 
is more than a yard long. How many inches are there in the 
meter stick ? How many centimeters in the meter ? Draw 
a line one centimeter long and write the abbreviation 1 cm. 
over it. How many millimeters in a centimeter? Divide 
the line you have just drawn into millimeters. What is the 
abbreviation for a millimeter? Using the small ruler 
measure the length of your Bunsen burner tube in centi- 
meters ; the diameter of the tube. Measure the length and 
diameter of a test tube and your beaker. 

B. Unit of Volume. 

The cubic centimeter is the unit most often used. Its 
abbreviation is cc. Draw a cube with each edge one centi- 
meter long. This represents a volume of one cubic centimeter. 
There are one thousand cubic centimeters in a liter. Ex- 
amine flasks with capacities of 1 1., 500 cc, 250 cc, and 100 
cc, respectively. From the size of your flask, as compared 
with these, what do you think is its volume ? Measure 1 cc. 
of water in your graduated cylinder ; measure 50 cc. (Read 
the lower part of the curved surface always.) Now, using 
the graduate, fill the flask and measure its volume. In like 
manner measure the volume of your beaker and test tube. 

C. Unit of Weight. 

The gram is the common unit of weight. Its abbreviation 
is g. Imagine the cube you have drawn in B to represent 
one cubic centimeter filled with water. The weight of this 
water would be about one gram. There are one thousand 
grams in a kilogram. If one cubic centimeter of water 



6 PRELIMINARY EXPERIMENTS 

weighs one gram, how many grams of water will your flask 
hold ? your beaker ? your test tube ? Learn how to use the 
balance, then weigh your beaker. 

Note : Return the meter sticks and rulers to the distributing table. Put 
away your apparatus. Clean and lock your desk as usual. 

D. Problems. 

1. A tank is 500 cm. long, 200 cm. wide, and 90 cm. deep. 
How many cubic centimeters of water will it hold ? 

2. If one cubic centimeter of water weighs one gram, 
how many grams of water will the tank in problem 1 
hold? 

3. A potato weighs 9 ounces. How many grams does it 
weigh ? 

4. What is your own weight in kilograms? 



EXPERIMENT 3 
How to Make Simple Apparatus from Glass Tubing 

Materials. Soft glass tubing, external diameter 5 mm. or 6 mm. 

(about 1 of an inch). 
Apparatus. Triangular file, fish-tail attachment for the Bunsen 

burner, meter stick or ruler, a Bunsen burner. 

Note to student: The laboratory notes will be mere statements of what 
you did. 

Note to teacher: Before entering the laboratory, show the students how 
to cut, bend, round sharp edges, and seal glass tubes. 

A. To Make a Glass Elbow or Delivery Tube. 

Glass elbows or delivery tubes are simple pieces of appa- 
ratus used to conduct gases from one vessel to another. To 
make a short one : (1) Cut off a piece of glass tubing 15 



HOW TO MAKE SIMPLE APPARATUS FROM GLASS TUBING 7 

cm. long (about 6 inches). (2) Bend at right angles in the 
middle and (3) smooth each end. Follow the instructor's 
directions as closely as possible. 

1. To cut a glass tube, place it on the table, measure off 
the required length, and at this point make a scratch with 
the triangular file. Pick up the tube with both hands. 
Place thumbs on both sides of the scratch and opposite it. 
Press up with the thumbs and down with the hands. The 
break should be even. 

2. To bend a glass tube, hold it lengthwise in the flat 
flame produced by the fish-tail attachment. Rotate it con- 
stantly until it is soft, then take it from the flame and bend 
it at right angles. Hold it so until it hardens. The bend 
should be smooth. Show it to the instructor for approval or 
advice before making a new one. 

3. The elbow cannot be used as it is because the sharp 
ends would cut the rubber stopper. Make each end smooth 
by heating it in the ordinary Bunsen burner flame till the 
glass begins to melt slightly. 

4. Make a long, glass elbow in the same way, using about 
30 cm. of tubing, making the bend about 8 cm. from 
one end. This also should be approved before it is put 
away. 

B. To Make a Stirring Rod. 

Cut off a piece of glass rod about 25 cm. in length. Heat 
the ends in a Bunsen flame till they are soft and round. 
Place it on the iron base of your ring stand to cool. Never 
put any hot glass or hot apparatus on the top of the table. 
After your rod has been approved put it away. Have your 
notes signed. 



8 PRELIMINARY EXPERIMENTS 

EXPERIMENT 4 

Physical and Chemical Changes 

Materials. Granulated cane sugar. 

Apparatus. Beaker, test tube, mortar and pestle, Bunsen burner, 
ring stand, wire screen, test tube holder. 

Note to teacher : It is convenient to measure out the proper amount of 
material on squares of paper on the distributing table ready for the students. 
This saves a great deal of time and material. 

A. How Sugar May Be Changed. 

1. Take a clean dry test tube and obtain about 10 grams 
of sugar from the distributing table. (Note : Be careful not 
to spill material on the distributing table — if you do, clean 
it up. Hold the stopper of the bottle in your hand and re- 
place it when you are through.) Carefully note the proper- 
ties of the sugar, its crystalline form, its hardness, color, and 
taste. How could you distinguish it from table salt ? What 
then is its most characteristic property ? 

2. Put about half of your sugar in a clean mortar and grind 
it till it is a powder. Taste it. Is it still sugar? Has its 
characteristic property been changed by grinding? This is 
a physical change, because the composition of the substance 
is unchanged, as is shown by the fact that no change in the 
characteristic properties has occurred. 

3. Fill your beaker one fourth full of water and add the 
powdered sugar from the mortar. Stir with your stirring 
rod until the sugar is dissolved. Taste the solution. Has the 
sugar been destroyed? What has happened to it? This is 
a physical change. 

4. Heat the remainder of the sugar in a dry test tube 
until it stops smoking. Note every change carefully. When 



ELEMENTS, COMPOUNDS, MIXTURES 9 

no further change takes place, cool the tube, break it, and 
examine the substance remaining in the tube. What is its 
form, its hardness, color, and taste? Will it dissolve in 
water ? Try it. Has the substance any properties of sugar ? 
This is a chemical "> change, because the composition is 
changed and a new substance is formed, having new prop- 
erties. 

B. How Other Substances May Be Changed. 

Tear a piece of paper into bits. Is the change physical 
or chemical? Why? Burn a piece of paper. Describe 
the change. Is it a physical or a chemical change ? 

C. Some Changes We See Every Day. 

Are the following changes physical, or chemical, or both? 
Give a reason for your answer in each case. 1. The souring 
of milk. 2. Making a batter from flour, milk, and eggs. 
3. Baking bread. 4. Making candy. 5. Beating an egg. 
6. Boiling an egg. 7. Freezing cream in making ice cream. 
8. Tarnishing of copper. 

Note : Have your notes signed. 

EXPERIMENT 5 
Elements, Compounds, Mixtures 

Materials. Sulfur, about 5-gram portions, magnesium ribbon, 
3 cm. strips, mixture of equal parts powdered sugar and sulfur, 
10-gram portions, Shaker Salt 10-gram portions. 

Apparatus. Evaporating dish, forceps, Bunsen burner, filter 
paper, funnel, stirring rod, two beakers. 

Note to teacher : Before entering the laboratory, show how to fold a filter 
and the correct method of filtering. 

Note to student: Take careful notes and have them signed before leaving 
laboratory. 



10 PRELIMINARY EXPERIMENTS 

A. Elements. 

1. Obtain 5 grams of sulfur in a test tube. Examine it 
carefully. What are its chief physical properties, i.e. color, 
odor, taste. Try to dissolve a little in a test tube half full 
of water. Is it soluble in water? Is sulfur a metallic or a 
non-metallic element? Can you find in the Appendix the 
names of three common non-metallic elements? 

2. Obtain a piece of magnesium ribbon about 3 cm. long. 
Notice its color and weight, its luster, and its flexibility. Is 
it a metallic or a non-metallic element ? Give the names of 
three common metals and give a use for each. 

3. Repeat 2, using aluminum instead of magnesium. 

4. Now tell in your own words what an element is. 

B. Compounds. 

1. Place a little sulfur about the size of a pea in your 
evaporating dish. Heat the sulfur by means of the burner 
flame till it burns. Very carefully note the odor. Is this 
a physical or chemical change ? We have noted the physical 
properties of sulfur in A, 1 . We have now observed one 
chemical property of sulfur. What is it? The gas that is 
formed when sulfur is burned is sulfur dioxide. It is a com- 
pound. 

2. By means of the iron forceps hold the piece of mag- 
nesium ribbon in the flame. Result? What is formed? 
Has the new compound any of the properties of the metal 
magnesium or the gas oxygen from which it was formed? 
In general, what is formed when an element burns in the air? 
Give a chemical property of magnesium. 

3. Repeat 2, using aluminum instead of magnesium. 
What is formed? Give a chemical property of aluminum. 



ELEMENTS, COMPOUNDS, MIXTURES 11 

4. Is sugar an element or a compound? How did you 
prove this in the preceding experiment? What is one ele- 
ment in it? Consult the textbook and find out the other 
elements in sugar. What are the elements in table salt 
(sodium chloride) ? in water ? 

5. What is a compound ? 

C. Mixtures. 

1. A well-known remedy for sore throat consists of a mix- 
ture of equal parts of sulfur and powdered sugar. Obtain 
from the instructor about ten grams of this remedy in your 
beaker. Fill the beaker half full of water and boil for about 
one minute, stirring occasionally. Which constituent of 
the remedy will dissolve? Which one will not? Remove 
the beaker from the ring stand and filter. The solid will 
remain on the paper and the liquid will pass through it. 

To prepare a filter paper fold it once and then again at 
right angles to the straight edge. Open the paper as a cone, 
with a triple layer of paper on one side and a single layer on 
the other. Place it in the funnel and moisten it well with 
water. The paper should not come to the top of the funnel. 
Place the funnel in the ring of the ring stand. Place the 
other beaker under the funnel. Adjust the ring so that 
the stem of the funnel extends into the beaker about one 
inch. To pour the liquid from the beaker into the funnel 
without spilling it hold the glass rod lightly against the rim 
of the beaker. -The liquid will flow down the rod. The 
liquid that goes through the filter paper is called the 
filtrate. 

Taste the filtrate. Where is the sugar? Where is the 
sulfur ? If a mixture consists of two substances, one soluble 



12 OXYGEN AND HYDROGEN 

in water and one insoluble, what is the general method of 
separating them ? 

2. "Shaker Salt" is pure sodium chloride (table salt) to 
which has been added a little starch to keep it dry. Starch 
is not soluble in water. Obtain ten grams of "Shaker 
Salt." Stir it into half a beaker of cold water. Is starch 
present ? 

3. Now define a mixture clearly. 

II. OXYGEN AND HYDROGEN 

EXPERIMENT 6 
Ways of Freeing and Collecting Oxygen 

Materials. Powdered potassium chlorate 8-gram portions, 
splints (about the size of a match and 7 inches long), 
powdered manganese dioxide 2-gram portions. 

Apparatus. Bunsen burner, test tubes, gas bottles, pneumatic 
trough, glass plates. 

A. How to Obtain Oxygen. 

1. Oxygen is the gas in the air which makes a fire burn. 
The air would be an excellent source of oxygen if it did not 
have so much nitrogen mixed with it. It is difficult to re- 
move the nitrogen and leave the oxygen. 

2. The compound potassium chlorate, KCIO3, is the most 
convenient source of oxygen. Obtain 8 grams of powdered 
potassium chlorate and 2 grains of manganese dioxide. 
Divide the potassium chlorate into two equal parts. Put 
one part (4 grams) in a clean, dry test tube. Mix the other 
part (4 grams) on a piece of paper with 2 grams of manganese 
dioxide (half as much), using the stirring rod. Then put 
it into a clean, dry test tube of the same size as the first. 



WAYS OF FREEING AND COLLECTING OXYGEN 13 

3. Heat the first tube gently and with a glowing splint 
test for oxygen. If oxygen is present, the glowing splint will 
burst into flame. Now heat the tube intensely and test for 
oxygen. What effect has increased heat? When oxygen is 
no longer given off, a new compound, potassium chloride, 
remains in the tube. 

4. Now heat the second tube containing the mixture of 

potassium chlorate and manganese dioxide. 

Important: If this mixture sparks (gives flashes of light), call the instructor 
to look at it. It means that the manganese dioxide contains carbon and is not 
safe to use in the next experiment. Small sparks are due to dust. 

Test with the glowing splint as before. The manganese 
dioxide undergoes no change. It causes the potassium 
chlorate to give up its oxygen at a lower temperature. It 
increases the speed of the reaction. What is such a sub- 
stance called? (Consult your textbook.) When oxygen is 
given off no longer, what is left in the test tube ? 

Note : To clean the test tubes in 3 and 4 fill them with water and let 
them stand overnight. 

B. How to Collect Oxygen and Other Gases. 

1. The most convenient method to collect a gas is by dis- 
placing water. Obtain a pneumatic trough and half fill it 
with water. Fill one of your gas bottles with water and slip 
a glass plate over the mouth, being careful to exclude all air 
bubbles. Hold the plate in place, invert the bottle in the 
water, and remove the plate. Raise the bottle a little ; never 
lift the mouth of the bottle out of water. Why does the 
water stay in the bottle? Hold the bottle in this position 
and fill it with air from the lungs by inserting one end of a 
rubber delivery tube in the mouth of the bottle and care- 
fully blowing through the other end. 

When the bottle is full of gas, cover its mouth with a glass 



14 OXYGEN AND HYDROGEN 

plate (still under water), remove from the water, and place 
it on the desk. A bottle of gas so covered is placed right 
side up if the gas is heavier than air, or upside down if the 
gas is lighter than air. 

2. A liter of air weighs 1.29 grams. A liter of oxygen 
weighs 1.43 grams. (See Appendix.) How then should a 
bottle of oxygen be placed ? 

3. A liter of hydrogen weighs .09 gram. Would you 
place the bottle upside down or right side up in this case in 
order to keep the hydrogen in the bottle the longest possible 
time? 

4. The gas carbon dioxide is soluble in water. It is heavier 
than air. How would you collect it ? How place the bottle ? 

5. The gas ammonia is also very soluble in water. It is 
lighter than air. How would you collect it? How place 
the bottle? 

EXPERIMENT 7 

Preparation and Properties of Oxygen 

Note to teacher: Each student understands that work in the laboratory 
must be done alone unless otherwise directed by you. Unless the laboratory 
periods are very long it has been found more satisfactory to allow two students 
to work together on this experiment. Discuss the experiment briefly and show 
how the apparatus is set up before students enter the laboratory. Place the 
" set up " in the laboratory so that they may use it as a model. 

Materials. 20 grams powdered potassium chlorate and 2 
grams of manganese dioxide mixed, pine splints, sulfur 1- 
gram portions, iron picture wire 15 cm. long. 

Apparatus. Pneumatic trough, four gas bottles (about 250 cc. 
each), four cover glasses, rubber delivery tube, short glass 
elbow, rubber stopper to fit large, hard-glass test tube, Bunsen 
burner, ring stand, test tube ciamp, combustion cup. 



PREPARATION AND PROPERTIES OF OXYGEN 15 

A. Preparation of Oxygen — Laboratory Method. 

1. Fill the pneumatic trough about half full of water. 
Fill four gas bottles with water, cover them, and invert in the 
trough as directed in Experiment 6, B. If a bottle has an 
air bubble, fill it again and invert. 

2. Attach the rubber delivery tube to the short glass 
elbow, put the elbow into the one-hole stopper, and fit the 
stopper into the large, hard-glass test tube. If it does not 
fit well, exchange it for one that does. All joints must be 
tight or the oxygen will escape into the air. Attach the 
test tube clamp to the ring stand and support the test tube 
in a slanting position. Do not pinch the tube tightly or it 
will break when you heat it. 

3. Obtain a mixture of 20 grams of potassium chlorate 
and 2 grams of manganese dioxide. Put into the hard-glass 
test tube, replace the stopper, and heat the mixture gently, 
at first holding the burner in the hand and moving the flame 
up and down on the tube. Put the end of the delivery tube 
in the water. The first bubbles are small and irregular 
bubbles of air. Soon large bubbles of oxygen should be 
evolved. Heat more gently if the gas comes too rapidly. 
Collect four bottles of gas. 

Caution : Remove the delivery tube before you stop heating or the water 
will be drawn back into the hot test tube and break it. Why will the water be 
drawn back in this way ? 

4. What substance produced the oxygen? Why was 
the manganese dioxide used? Write in words the equation 
for the reaction that took place thus : 

Potassium Chlorate + heat — ^Potassium Chloride + Oxygen 
KC10 3 +heat— >■ KC1 +30 



16 OXYGEN AND HYDROGEN 

Since the manganese dioxide was not changed in any way, it 
would not appear in the equation. 

B. Physical Properties of Oxygen. 

The physical properties of a gas are its color, odor, taste, 
its solubility in water, and its weight as compared with air. 

1 . Uncover a bottle of oxygen, smell it, and inhale some of 
it through the mouth. Has it any odor or taste? Has it 
any color? Is it soluble in water? Is it heavier or lighter 
than air? Recall Experiment 6, B, 2. 

2. Summarize the physical properties of oxygen. 

C. Chemical Properties of Oxygen. 

Chemical properties are those that are shown where a 
substance undergoes a chemical change. 

1. Thrust a glowing splint into a bottle of oxygen. Re- 
move it, blow out the flame, and thrust it in again. Do this 
as many times as you can. After a while the stick will not 
burst into flame. Why? Does oxygen burn? Does it 
support combustion (make other things burn) ? What gas 
is now in the bottle? W T as this a physical or chemical 
change? Write in words the equation for the reaction. 

2. Obtain 1 gram of sulfur in your evaporating dish. 
Place half of this in your combustion cup. Hold it over the 
flame until it starts to burn. Notice the color and size of 
the flame. What is the gas formed when sulfur burns in 
air or in oxygen? Thrust it quickly into a bottle of oxygen. 
Notice the change in the flame. What is the gas formed? 
Write the equation in words to show what took place. Was 
this a physical or chemical change ? 

3. Fray one end of a piece of iron picture wire. Heat the 
frayed end and then dip it into the sulfur in your evaporating 



WHAT TAKES PLACE WHEN A SUBSTANCE BURNS 17 

dish. The wire is frayed and dipped in sulfur in order that 
it may start to burn more readily. Hold the wire in the 
flame till the sulfur burns, then thrust it into a bottle of oxy- 
gen. Result? Will iron burn in the air? What new sub- 
stance was formed in the bottle? What kind of change 
took place? Write in words the equation for the reaction 
that took place. When a substance burns in oxygen, what 
is always formed ? 

4. From these tests what is the chief chemical property 
of oxygen ? 

Note: Empty the pneumatic troughs and return them. Burn the sulfur 
out of the combustion cup before returning it. 



EXPERIMENT 8 
What Takes Place When a Substance Burns 

Note : This should be a class experiment if hoods are not available or if the 
class is large. It is a dangerous experiment. 

Materials. Yellow phosphorus, red phosphorus, sulfur (small 
amounts about the size of a pea), sulfur matches, parlor matches, 
safety matches. 

Apparatus. Bunsen burner, asbestos mat, forceps. 

A. Slow Oxidation. 

1. Half fill your evaporating dish with water and take 
it to the instructor for a piece of yellow phosphorus the size 
of a pea. Lift it out of the dish with the forceps and place 
it upon your asbestos mat. Take Care ! Do not Touch 
It with the Fingers. What are its physical properties? 
As soon as the phosphorus becomes dry, do heavy white 
fumes arise? What are these fumes? Do you notice any 
light or heat ? What is taking place ? 



18 OXYGEN AND HYDROGEN 

2. When iron rusts, what is formed ? Is there any notice- 
able light or heat ? What is this process called ? 

B. Rapid Oxidation or Burning (Hood). 

1 . Carefully place a small amount (about the size of a pea) 
of sulfur one inch from the phosphorus. About the same 
distance away place a small amount of red phosphorus. 
The same distance away place a piece of pine splint. Raise 
the temperature of all by slowly heating with the burner 
turned low. Stand back and observe the order in which 
the substances take fire and burn. 

2. Explain what takes place when a substance burns in 
the air. 

3. What is meant by the kindling temperature of a sub- 
stance ? 

4. Why is phosphorus kept under water? 

5. Why was the untwisted picture wire tipped in sulfur 
before putting it in oxygen to burn ? 

6. Why are paper and kindling wood used to build a coal 
or wood fire ? 

7. Lacking kindling wood, kerosene is sometimes poured 
upon the coal or wood. Is this safe? Why? 

C. The Study of Matches. 

1. Examine the head of a sulfur match. The color, usually 
red, is merely a dye. Rub the head upon your moist hands 
in the dark. What causes the glowing streak? Smell the 
match head after rubbing it on your hand. W 7 hat is in the 
tip of the match? Remembering the color of sulfur, see if 
you can observe sulfur on the wood next to the match head. 
Rub a match on a rough surface. What takes fire first? 
What produces the heat to raise it to its kindling tempera- 



PREPARATION AND PROPERTIES OF HYDROGEN 19 

ture ? What burns last ? What produces the heat to make 
it catch fire? Name in order the substances in a sulfur 
match that burn, beginning with the one that has the lowest 
kindling temperature. 

2. Examine a parlor match in like manner. What is used 
in place of the sulfur in this match? Name in order the 
substances in a parlor match that burn, beginning with the 
one that has the lowest kindling temperature. 

3. W T hat is a safety match? Why is it safe? Where 
must it be scratched ? 

Caution: Be sure that all of the phosphorus is burned from your mat before 
you put it away. See that no phosphorus clings to the forceps. If you have 
any unused sulfur matches or parlor matches, return them ; it is not safe 
to put them away in the drawer or locker. 

EXPERIMENT 9 
Preparation and Properties of Hydrogen 

Note to teacher : Before the students enter the laboratory discuss the ex- 
periment briefly and show how the apparatus is set up. Leave your " set up" 
before them as a model. Supervise closely, to avoid explosions. 

Materials. Granulated zinc 10-gram portions, splint, dilute 

sulfuric acid. 
Apparatus. A 250-cc. Florence flask, two-holed stopper, short 

elbow, delivery tube, pneumatic trough, four gas bottles, beaker, 

two test tubes, and a safety tube. 

A. The Usual Method of Preparing Hydrogen by Action of a Metal on 
an Acid. 

1. Carefully slip 10 grams of zinc into your flask; insert 

the stopper containing the safety tube and delivery tube. 

Keep the flask in an upright position by clamping it to the 

ring stand. Half fill the pneumatic trough with water and 

invert in it four gas bottles filled with water, as in the case of 



20 OXYGEN AND HYDROGEN 

oxygen. Have the four cover glasses near the trough ready 
for use when the bottles are full. Also fill two test tubes 
with water and invert them in the trough. (They may lie 
in the water on the bottom of the trough till you are ready 
for them.) Remove the stopper from a bottle of sulfuric 
acid by grasping it between the first two fingers of the right 
hand, palm up. Pick up the bottle with the same hand and 
pour acid into the thistle tube. Just touch the mouth of 
the bottle to the lip of the tube. Pour in acid till the zinc is 
covered. Then replace the bottle and the stopper. Always 
follow these directions when pouring a liquid from a bottle. 
Never put the stopper on the table or shelf, and if too much 
liquid is taken, never return any to the bottle. Keep it in a 
labeled test tube for future use or throw it into the sink. 

If hydrogen comes from the acid very slowly, add through 
the thistle tube 5 or 10 cc. of copper sulfate solution. Why 
does this increase the action? Be sure that the apparatus 
is air tight. 

2. Light the Bunsen burner. Caution ! Keep it some 
distance from the apparatus, because at first the hydrogen 
is mixed with air and the mixture is explosive. 

3. Allow the gas to escape into the air for about one 
minute, then collect a test tube of it. Put the thumb over 
the mouth of it and bring the tube, mouth downward, to 
the flame. If it explodes, the hydrogen is still mixed with 
air. Collect another test tube and try again. When the 
gas burns with a little puff at first, it is ready to be collected 
in the gas bottles. Collect four bottles of hydrogen ; cover 
them and invert them on the desk. If the action stops before 
the bottles are filled , add a little more acid. Why remove 
the deliverv tube from the water ? 



PREPARATION AND PROPERTIES OF HYDROGEN 21 

4. Where does the hydrogen come from? What was the 
use of the zinc ? Could any other metal have been used ? 

B. Physical Properties of Hydrogen. 

1 . Examine a bottle of hydrogen ; note its color, taste, 
and odor. (There may be a slight odor due to an impurity.) 

2. Is it soluble in water? How do you know? 

3. Uncover a bottle of hydrogen ; hold it mouth upward 
while you count thirty, then test for hydrogen. Explain the 
results. Is the gas heavier or lighter than air? 

C. Chemical Properties. 

Hold a bottle of hydrogen mouth downward and quickly 
thrust a blazing splint into the bottle. Withdraw the splint 
and insert it again. Does the hydrogen burn ? If so, where ? 
Does the splint burn when in the bottle? when out of the 
bottle? Does hydrogen support combustion? Feel the 
neck of the bottle. Describe and explain. What proper- 
ties of hydrogen are shown by this experiment ? 

D. What Remains in the Flask. 

1. Pour the liquid from the flask into a beaker. Return 
the pieces of zinc to the instructor. Put the beaker in the 
locker until the next laboratory period. Then examine the 
contents of the beaker. What are the crystals? Did a 
physical or chemical change take place ? 

2. The equation for the reaction is as follows : 

Sulfuric Acid + Zinc — >- Zinc Sulfate + Hydrogen 
H 2 S0 4 + Zn — >■ ZnS0 4 + 2H 

Hereafter, all equations will be written in this manner — 
first in words, then using formulas for the compounds and 
symbols for the elements. What are the compounds in the 



22 OXYGEN AND HYDROGEN 

reaction ? Name each, and give the formulas for each. 
What is the metallic element? Give its symbol. What is 
the non-metallic element? Give its symbol. 

EXPERIMENT 10 

(Class Experiment) 

Two Other Methods of Preparing Hydrogen 

Note : In A 4 be sure that the tin foil is wrapped so tightly about the sodium 
that no air is included or an explosion may result. 

Materia.". Sodium, potassium, sulfuric acid, distilled water. 

Apparatus. Pneumatic trough, knife, tin foil, iron or copper 
wire, 250 cc. gas bottle, glass plate, Hoffman apparatus, stor- 
age battery. 

A. By the Action of Metals on Water. 

1. Note the physical properties of sodium and potassium. 

2. Cut off a piece of sodium the size of a pea and throw it 
upon the water in the pneumatic trough. What is the re- 
sult? Explain. 

3. Repeat, using potassium instead of sodium. Note the 
results. Explain. 

4. With the sharp end of a file punch small holes in a 
piece of tin foil and wrap it firmly around a piece of sodium 
about the size of a large bean. Fill a 250 cc. gas bottle with 
water and invert it in the trough. Raise the bottle slightly 
and by means of a wire quickly thrust the sodium under 
the mouth of the bottle. When the bottle is full of gas, con- 
tinue to hold the sodium under water till the action ceases. 
Then cover the bottle with a glass plate and remove from the 
water. Bring a flame to the bottle and uncover it. Explain 
the results. 



TWO OTHER METHODS OF PREPARING HYDROGEN 23 

5. What is the gas? Where did it come from? Why 
was the flame colored yellow in this case? Now explain 
the flame when potassium was thrown on the water. 

6. What method of preparing hydrogen is shown by this 
experiment? What is one of the elements in water? 

7. Test the water with pink litmus. What is dissolved 
in the water? Write a word-and-symbol equation to show 
what has taken place. 

B. By the Action of the Electric Current on Water. 

1. Fill a clean Hoffman apparatus with pure distilled 
water. Connect the platinum terminals with an electric 
battery. Is a gas given off at either terminal? Does pure 
water conduct an electric current ? 

2. Fill the Hoffman apparatus with water containing 10 
per cent of sulfuric acid, so that the water in the reservoir 
tube stands a short distance above the gas tubes after the 
stop-cock in each has been closed. Connect the platinum 
terminal wires with the battery. Allow the current to oper- 
ate until the smaller volume of gas is from 8 to 10 cm. 
in height. Measure the height of each gas column. 

3. Hold a glowing splint over the tube containing the 
smaller quantity of gas. What is the gas that collects at the 
positive electrode (anode) ? Open the other stop-cock to 
force out the water in the glass tip, then hold a lighted match 
at the end of the tip. What is the gas that collects at the 
negative electrode (cathode) ? Make a drawing showing 
the anode and cathode and the relative volume of gases col- 
lected over each. 

4. If the current were allowed to flow long enough, all the 
water would be used up. The sulfuric acid would remain. 



24 WATER 

What is the use of the sulfuric acid ? Could any other sub- 
stance have been used? 

5. What does this experiment show about the composi- 
tion of water? Write the word-and-symbol equations to 
show what takes place on the electrolysis of water. 

6. In what three ways may hydrogen be prepared? 

7. In what four ways have you prepared oxygen ? 



III. WATER 

EXPERIMENT 11 

(Class Experiment) 
The Synthesis of Water 

Materials. Calcium chloride, copper oxide, wire form. 

Apparatus. Hydrogen generator, calcium chloride tube, de- 
livery tube, clay pipestem, bell jar, hard glass combustion 
tube 7 inches long. 

A. Synthesis of Water by Burning Hydrogen. 

1. Connect a calcium chloride tube with a hydrogen gen- 
erator (a Kipp generator is best). How is the hydrogen 
generated? Why is the calcium chloride tube used? All 
joints must be air-tight. Attach a delivery tube to the cal- 
cium chloride tube, and collect a test tube full of hydrogen 
by displacement of water. If it burns quietly, remove the 
delivery tube and attach a platinum jet or a clay pipestem 
jet. Why test the gas before it is lighted? Allow the hy- 
drogen to pass for a full minute and then hold a bell jar 
over the tip. Note any change. 

2. Remove the jar, light the hydrogen, and again hold 
the bell far over the jet. Note any change in the jar. 



HOW TO TEST HYDROGEN AND WATER 25 

3. What is formed when hydrogen burns in the air? Of 
what elements is water composed? Write the word-and- 
symbol equation to show the change that takes place. 

B. Reduction and Oxidation. 

1 . Use the same apparatus as in A. Attach to the calcium 
chloride tube a straight glass tube and extend this into a hard- 
glass test tube containing 1 gram of copper oxide, wire form. 

2. When the apparatus is free from air, heat the copper 
oxide, being careful not to heat the top of the test tube. 

3. W T hat change takes place in the copper oxide? What 
collects on the cool sides of the test tube ? Write the word- 
and-symbol equation for the change that took place. 

4. When oxygen or other non-metal is removed from a sub- 
stance, it is called reduction. Is hydrogen a good reducing 
agent in this case ? Why ? 

5. When oxygen or other non-metal is added to a substance, 
the process is called oxidation. Is copper oxide an oxidizing 
agent in this case ? Why ? 

6. What is meant by the word synthesis f In what two 
ways was water synthesized in this experiment ? 

EXPERIMENT 12 
How to Test Hydrogen and Water 

Materials. Pine splint, sugar, corn starch, alum crystal, crys- 
tals of sodium carbonate, crystalline calcium chloride, potato, 
meat, apple. 

Apparatus. Bunsen burner, cold glass plates, test tubes. 

A. Test for Hydrogen in Substances. 

From Experiment 1 1 you learned that when hydrogen is 
burned in the air, it combines with the oxygen of the air to 



26 WATER 

form water. If then water is formed when a substance is 
burned in air, the substance must contain hydrogen. 

1. Light the Bunsen burner. Hold a cold dry glass plate 
over the flame. Note any moisture on the plate. Does 
ordinary gas contain hydrogen ? Now explain why the cold 
bottom of a kettle or a cold flatiron becomes moist when 
they are first placed over a flame. Why does the moisture 
disappear after a time ? 

2. Why does the inside of a kerosene lamp chimney be- 
come covered with moisture when the lamp is first lighted? 
This moisture disappears in a few minutes. Why? 

3. Burn a pine splint and hold a cold dry plate above the 
flame. Does wood contain hydrogen ? 

B. Test for Hydrogen and Oxygen in Substances. 

Some substances v contain both hydrogen and oxygen. 
When these substances are heated till they decompose, the 
hydrogen in the substance combines with the oxygen in the 
substance to form water. The substance must not be burned. 
This test proves the presence of both hydrogen and oxygen 
in a compound. 

1 . Heat 5 grams of sugar in a dry test tube till it is com- 
pletely decomposed. Keep the neck of the tube as cold as 
you can and look for drops of water on the sides of the tube. 
What are two elements in sugar? In what proportion are 
these elements present in sugar ? Does sugar contain water ? 
What remains in the test tube? Write a word-and-symbol 
equation for the reaction that took place. 

2. In like manner heat 5 grams of corn starch. Ex- 
plain what takes place. Write the word-and-symbol 
equation. 



HOW TO TEST HYDROGEN AND WATER 27 

C. Test for Water in Substances. 

Many substances contain water held in such a way as to 
give the substance its form. Water so held may be removed 
by heating the substance gently without burning it or decom- 
posing it. 

1. Heat a crystal of alum in a dry test tube. Is water 
given off? What happens to the crystal? 

2. Heat a crystal of sodium carbonate (washing soda) 
in the same way. Result? When crystals of sodium car- 
bonate are exposed to the air they give up water to the air 
and they fall to a powder. Wliat is this process called? 
Would it be cheaper to buy clear crystals of washing soda or 
to buy the substance after it has become a powder from long 
standing in the air? Why? 

3. Heat a crystal of calcium chloride in a dry test tube. 
Result? Now leave exposed to the air some calcium 
chloride which has been so heated. Result? Explain: 
Why does ordinary table salt sometimes become moist and 
hard to shake from the salt cellar? What is sometimes 
added to prevent this? 

4. Nearly all foods and substances of plant and animal 
life contain water. Heat in a cool dry test tube portions 
about the size of a bean of the following substances. Be care- 
ful not to burn or decompose the substances. 









1. 


Wood 












2. 


Potato 












3. 


Meat 












4. 


Apple 












5. 


Nut 






What 


do 


you 


conclude 


about the 


general 


distribution 


of water 


? 













28 WATER 

EXPERIMENT 13 
The Solvent Power of Water 

Note to teacher: To avoid repeated weighings small measures may be 
made out of glass tubing (not too small inside diameter) sealed at one end. 
Weigh out the required amount of the substance. Jar it into the closed end 
of the tube and cut off the portion filled with the substance. Place about this 
a strong gummed label bringing the ends together for a handle. 

Materials. Bottles of soda water (one bottle for each four stu- 
dents), alcohol, kerosene, carbon disulfide, powdered copper 
sulfate, sodium thiosulfate. 

Apparatus. Beaker screen, test tubes, thermometer. 

A. Solubility of Gases. 

Note : Four students may use one bottle of soda water. 

1. Remove the cap from a bottle of soda water. What 
causes the bubbling or the effervescence? How is the 
pressure on the liquid in the bottle changed when the cap is 
removed from the bottle ? How does change of pressure 
affect the solubility of a gas ? 

2. Pour one fourth of a bottle of soda water into your 
beaker (each student alone). Set this on a wire screen on 
the ring stand and warm with the burner. Do not heat to 
a boiling point of water. Why? How does the rise in 
temperature affect the solubility of a gas? 

Throw away the soda water and half fill the beaker 
with cold water from the faucet and warm it over the burner. 
Explain the appearance of small bubbles on the inside of the 
beaker. 

If a glass of ice water is allowed to stand, bubbles appear 
clinging to the inside of the glass. Give your explanation 
of this phenomenon. 



THE SOLVENT POWER OF WATER 29 

B. Solubility of Liquids. {No flames.) 

1. Half fill a test tube with water. Add 5 cc. of alcohol. 
Shake and look for layers. If a liquid does not dissolve in 
water, it will form a layer above it if it is lighter than water, 
or below it if it is heavier than water. Does alcohol dissolve 
in water? 

2. Repeat (1), using kerosene. Will it dissolve? Is it 
lighter or heavier than water? 

3. Repeat (1), using carbon disulfide. Will it dissolve? 
Is it lighter or heavier than water? 

C. Solubility of Solids. (Instructor's Experiment.) 

1. Put exactly 50 cc. of water in a beaker and add 1-gram 
portions of powdered copper sulfate as long as it will dissolve ; 
that is, as long as the solution is unsaturated. Stir con- 
stantly to aid solution. When no more will dissolve, the solu- 
tion is saturated: Note the temperature. How much copper 
sulfate will dissolve in a cubic centimeter of water at this 
temperature? This is the solubility of copper sulfate for 
that temperature. 

2. Heat the saturated solution of copper sulfate over a 
Bunsen burner flame and add powdered copper sulfate again 
in 1-gram portions until no more will dissolve. Note the 
temperature. What is the solubility of copper sulfate at 
this temperature? How does the rise in temperature affect 
the solubility of copper sulfate ? 

3. Cool the solution by allowing cold water to flow over 
the beaker. • Explain. 

4. Repeat the experiment, using some other salt in place 
of copper sulfate. Does the rise in temperature increase the 
solubility of all substances alike ? 



30 WATER 

5. Heat fifty or sixty grams of sodium thiosulfate crystals 
in a large test tube until they dissolve in the water they con- 
tain, forming a saturated solution. Without shaking the tube 
cool it in running water. Then the solution is supersaturated 
at this temperature, yet no crystals of sodium thiosulfate 
appear. Now add a crystal of the salt and note the sudden 
formation of crystals and the rise in temperature. 1 

6. Given a solution of salt how would you prove that it 
was unsaturated, saturated, or supersaturated? 

EXPERIMENT 14 
Boiling Point and Freezing Point of Water 

Thermometers 

Materials. Ice, salt. 

Apparatus. Two-hole rubber stopper, short glass elbow, centi- 
grade and Fahrenheit thermometers, flask and screen, test 
tube, beakers. 

A. Boiling Point of Water. 

1. Fit the two-hole rubber stopper with a centigrade 
thermometer and a short glass elbow. 

Note: Wet the thermometer and tube before inserting and twist them into 
place — do not try to push it in or you may break your thermometer and cut 
your hand. Insert the stopper in a flask containing about ioo cc. of pure water. 
If the thermometer is not immersed in the water, remove the stopper and push 
the thermometer further through until it is immersed when the stopper is re- 
placed. 

2. Clamp the flask carefully on the ring stand over the 
ring and wire screen. Heat the water till it boils and note 

1 This principle is made use of in certain " waterless hot water 
bottles " on the market. These bottles are metal and filled with 
sodium thiosulfate crystals. If put into boiling water for ten minutes, 
the crystals dissolve. The bottle will then remain hot for some hours 



BOILING POINT AND FREEZING POINT OF WATER 31 

the temperature when it becomes constant. Apply more 
heat by turning up the flame. Does the temperature change ? 
Explain. 

3. What is the boiling point of water on the centigrade 
scale ? 

4. Now raise the thermometer out of the water so that 
it will be in the steam only as the water boils. Boil the water 
and note the temperature of steam. Explain. 

5. Obtain a Fahrenheit thermometer and repeat the experi- 
ment. What is the boiling point of water on this scale ? 

6. Replace the centigrade thermometer in the stopper. 
Add ten grams of table salt to the water. Shake until it 
dissolves. Note the boiling point. How does salt dissolved 
in water affect its boiling point ? 

B. Freezing Point of Water. 

1. Put some pieces of ice in your 150 cc. beaker and add 
about 25 cc. of water. Carefully stir the mixture with the 
centigrade thermometer until the temperature is constant. 
What is the melting point of ice, centigrade scale? 

2. Repeat, using a Fahrenheit thermometer. What is 
the melting point of ice, Fahrenheit scale? 

3. Make a freezing mixture in your 250 cc. beaker 
by mixing three parts of cracked ice with one part of 
common salt. Why is the temperature of such a mixture 
below the freezing point of water ? 

Half fill a test tube with pure water and place the tube in 

or as long as a real hot water bottle would remain hot, for it cools down 
slowly from 100° C.to room temperature. The solution is then super- 
saturated, and if the stopper of the bottle is removed and a wire thrust 
into the liquid, crystals will form and heat will be given off for several 
hours longer. 



32 WATER 

the freezing mixture. Note the temperature, centigrade 
scale, at which the water begins to freeze. How does the 
freezing point of water compare with the melting point of ice ? 

C. Problems in Temperature. 

1. Note the room temperature on the centigrade ther- 
mometer. 

From the formula F. = fC.+32 (see Appendix) calculate 
the temperature of the room on the Fahrenheit scale. Now 
read the Fahrenheit thermometer hanging in the room. 

2. On a very warm day the temperature may be 98° F. 
What would this be on the centigrade scale ? Use the formula 
C. = |(F.-32). (See Appendix.) 

3. The normal temperature of the human body is 98° F. 
In fever cases the temperature may run up to 106° F. What 
would these temperatures be on a centigrade thermometer? 

4. The hottest part of the Bunsen flame is 860° C. What 
would this temperature be on the Fahrenheit scale ? 

5. Alcohol boils at 78° C. and solidifies (freezes) at —130° 
C. What would these temperatures be on the absolute 
scale? (See Appendix.) 

EXPERIMENT 15 
How to Purify Water 

Materials. Distilled water, salt, bone black, dirt, potassium 
permanganate solution. 

Apparatus. Watch glass, screen, funnel, filter paper, one round- 
bottomed distilling flask, a Florence flask, condenser. 

A. How to Show the Presence of Salts Dissolved in Water. 

1. Put a few drops of distilled water on your watch glass. 
Place this on the wire screen and slowly evaporate it by 



HOW TO PURIFY WATER 33 

moving the flame back and forth below it. Is there a 
residue ? 

2. Now place a few drops of faucet water on the glass and 
evaporate. A residue indicates something dissolved in the 
water. Does the city water contain dissolved salts? 

3. What other impurities besides dissolved salts may a 
water contain ? 

B. Impurities Removed by Filtration. 

1. To some water add dirt, some table salt, and some 
potassium permanganate to give it color. Place a filter in a 
funnel and into this pour a thin paste of bone black and 
water. When this has settled, pour on to it some of the tur- 
bid, salty, colored water. Is the turbidity removed ? Is the 
color removed ? Is the salt removed ? Test this by evapo- 
rating a few drops on a watch crystal as before. Would 
dangerous germs or poisonous organic matter be removed? 

2. What impurities are removed by filtration? 

C. Impurities Removed by Distillation. (Instructor's Experiment.) 

1. Place about 100 cc. of the same turbid water in a round- 
bottomed distilling flask and connect the flask to the con- 
denser. Why should the water enter the lower opening of 
the condenser jacket? The water flows out of the upper 
opening through a rubber tube to the sink. Heat the flask 
over a screen until the water boils. The steam from the 
boiling water is condensed in the cool condenser tube and 
collected in a flask. The condensed liquid is called the distil- 
late. The process is distillation. 

2. Note the color and taste of the distilled water. Test 
for salt by means of the watch glass as before. 

3. Where is the salt and coloring matter? What impuri- 



34 WATER 

ties may be removed by distillation? What impurities may 
not be removed in this way ? 

4. Which is the better water to drink, filtered water or 
distilled water ? Give all the reasons that you can for your 
answer. 

5. What is the source of the drinking water in your city? 
What impurities are present in this water ? What attempts, 
if any, are made by the city to remove them ? How could 
you make the water more fit for drinking purposes at home? 

EXPERIMENT 16 

Properties of Hydrogen Peroxide 

Materials. Hydrogen peroxide, litmus paper, manganese di- 
oxide, dark hair, ammonium hydroxide. 
Apparatus. Large test tube, splint, filter paper funnel. 

A. Properties of Hydrogen Peroxide. 

1 . What is the formula of hydrogen peroxide ? How does 
it differ in composition from water? 

2. What is the hydrogen dioxide sold by druggists? 

3. Place 5 cc. of hydrogen peroxide in a large test tube. 
Test with a small piece of litmus paper. Explain. 

4. Add 2 grams of powdered manganese dioxide. Thrust a 
glowing splint into the tube. What gas is given off? Write 
the equation. Filter the mixture remaining in the tube. 
What is the residue ? What was the purpose of the manga- 
nese dioxide ? 

5. Why should bottles of hydrogen peroxide be kept tightly 
stoppered? Why are the bottles always dark in color? 

6. Why are the corks of the hydrogen peroxide bottles so 
white? 



PREPARATION AND PROPERTIES OF NITROGEN 35 

B. Uses of Hydrogen Peroxide. 

1. Wash some dark hairs free from oil, then immerse them 
for one hour in 10 cc. of hydrogen peroxide made alkaline 
with ammonium hydroxide. Remove them and allow them 
to dry. Result ? Hydrogen peroxide is used to bleach wool 
and silk. 

2. Give some of its uses as a disinfectant. 



IV. NITROGEN AND THE AIR 

EXPERIMENT 17 

Preparation and Properties of Nitrogen 

Materials. Phosphorus, charcoal, pine splints, 4 g. ammonium 

chloride, and 8 g. -sodium nitrite mixed. 
Apparatus. Wide-mouthed bottle, cover glasses, glass pneumatic 

trough, 250 cc. flask, one-hole stopper, delivery tube, troughs, 

2 gas bottles, ring stand, gauze. 

A. Nitrogen from the Air. (Instructor's Experiment.) 

Nitrogen and oxygen are the chief gases of the air. If 
phosphorus is burned in a bottle of air, it will combine with 
the oxygen, forming phosphorus pentoxide. If there is water 
in the bottle, the phosphorus pentoxide will dissolve in the 
water and nitrogen will be left in the bottle. 

1. Pin a piece of phosphorus about the size of a pea to a 
piece of charcoal. Float the charcoal on the water in the 
glass trough. Light the phosphorus and quickly cover it 
with a large, wide-mouthed bottle. Keep the neck of the 
bottle pressed well down into the water. With what was the 
bottle filled when it was placed over the burning phos- 
phorus? What is the "smoke" that is formed as the 



36 NITROGEN AND THE AIR 

phosphorus burns? What constituent of the air is being 
removed ? 

2. Allow the bottle tc stand till the " smoke" has dissolved 
in the water and the gas in the bottle is clear, then make the 
water level the same inside as outside the bottle. Why has 
the water risen in the bottle? The gas remaining is chiefly 
nitrogen. About what part of the air is nitrogen? 

3. Cover the mouth of the bottle with a glass plate and 
invert, taking care not to lose any of the water that has risen 
in the jar. What are the physical properties of nitrogen in 
the jar? What are the physical properties of the nitrogen 
in the air? Is the nitrogen in the bottle pure? Why? 

4. Thrust the burning splint into the bottle of nitrogen. 
Result? Repeat, using phosphorus. Result? Does it 
burn ? Does nitrogen support combustion ? 

B. Preparation of Pure Nitrogen. Note : Instructor's Experiment, 
unless Class Is Very Small. 

1. Obtain a mixture of 4 grams of ammonium chloride 
and 8 grams of sodium nitrite. Place this in a 250 cc. flask 
and add 25 cc. of water. Fit a one-hole rubber stopper and 
a delivery tube to the flask in order that the gas may be col- 
lected over water as in case of oxygen. Clamp the flask to 
the ring stand over a wire gauze and heat very gently by 
moving the burner about with the hand. As soon as action 
begins, stop heating. If the action becomes too violent, lower 
the wire gauze and raise a bowl of water until the flask is 
immersed in it and cooled. 

When the air is expelled from the flask (about one minute), 
fill two gas bottles with nitrogen. 

2. The reaction that takes place in the preparation of 
pure nitrogen may be expressed in two equations. (1) The 



THE COMPOSITION OF THE AIR 37 

ammonium chloride and the sodium nitrite react to form 
ammonium nitrite and sodium chloride : 

NH 4 Cl+NaN0 2 — ^ NH 4 N0 2 +NaCl 
(2) The ammonium nitrite then decomposes into water 
and nitrogen : 

NH 4 N0 2 — »- 2 H2O+N2 

Write these two equations for the preparation of nitrogen, 
naming all substances used and formed. 

3. Using one bottle of the gas, note its physical properties, 
i.e. its color, odor, taste. 

Is it soluble in water ? 

Is it heavier or lighter than air ? (See Appendix.) 

4. Into the other bottle of gas thrust a burning splint. 
Does nitrogen burn ? 

Does nitrogen support combustion ? 

EXPERIMENT 18 

The Composition of the Air 

Materials. Phosphorus, splint, limewater, calcium chloride. 
Apparatus. Glass trough, graduated tube 100 cc. or 250 cc., 

wire, cover glasses, beaker, long glass elbow, test tube, gas 

bottle. 

A. The Per Cent of Nitrogen and Oxygen in the Air. (Instructor's 
Experiment.) 

1. Half fill a glass trough or battery jar with water. 
Invert into the jar a graduated tube (about 100 cc or 250 cc). 
Adjust so that the water within and without the tube stands 
at the same level. Why ? Note the volume of air in the tube. 

2. Place a piece of phosphorus on the tip of a wire and 
insert in the tube. Push up the wire till the phosphorus 



38 NITROGEN AND THE AIR 

is in the upper part of the tube. Be careful not to lift the 
mouth of the tube from the water. 

What are the white fumes that come from the phosphorus ? 
What causes the fumes? What gas is being used up? 

3. Allow the apparatus to stand until the next day. Note 
the position of the water. Why has it risen in the tube? 
Are white fumes rising from the phosphorus now? Why? 
What is the gas that remains in the tube ? 

4. Lower the tube until the water within and the water 
without the tube stands at the same level. Why? Note 
the volume of the gas in the tube. 

5. Slip a cover glass over the mouth of the tube and re- 
move it from the jar. To further test the remaining gas 
thrust into the tube a blazing splint. Does the gas burn? 
Does it support combustion ? What is the gas ? 

6. Record your observations and calculate the per cent of 
nitrogen in the air, as follows : 

(a) Volume of air at the beginning of experiment = cc. 

(6) Volume of nitrogen at the end of the experiment = cc. 

(c) Volume of oxygen removed by the phosphorus = cc. 
Volume of oxygen (c) 

= volume of air (a) — volume of nitrogen (6). 

The per cent of nitrogen by volume in the air is found as 
follows : 

Volume of nitrogen (6) X 100 _ ., 

A7 , ! . ' — -- % nitrogen 

Volume ot air (a) 

The per cent of oxygen by volume in the air is found in like 
manner : 

Volume of oxvgen (c)XlOO _ 

Volume ot air (a) 



THE COMPOSITION OF THE AIR 39 

B. Carbon Dioxide in the Air. (Student's Experiment.) 

1. Place about 5 cc. of limewater in a clean beaker and 
leave it exposed to the air until the close of the laboratory 
period. Note the white crust formed on the surface of the 
limewater. This proves the presence of carbon dioxide in 
the air. 

2. Through the long glass elbow blow air from the lungs 
into 5 cc. of limewater in a test tube. Explain results. This 
is one source of carbon dioxide in the air. 

3. Place a burning splint in a bottle of air. In a short 
time the splint will go out. Why? Remove the splint and 
quickly cover the bottle with a glass plate. Add 5 cc. of 
limewater and shake. Results? How does this experi- 
ment show another source of carbon dioxide in the air? 

4. Name three other sources of carbon dioxide in the 
air. 

5. If animals are constantly exhaling carbon dioxide, why 
does not the per cent of oxygen greatly decrease and the 
per cent of carbon dioxide increase as time goes on ? 

C. Water Vapor in the Air. 

1. Place a piece of calcium chloride on a watch glass or 
in a dry beaker and leave it exposed to the air overnight. 
(Lock it in your drawer.) In twenty-four hours look at it 
again. Explain. A substance that will take up water 
from the air in this way is a deliquescent substance. Such 
substances are good drying agents. 

2. In what other way could you prove the presence of 
water vapor in the air ? 

3. What are some of the sources of water vapor in 
the air ? 



40 NITROGEN AND THE AIR 

EXPERIMENT 19 
Ammonia, NH 3 

Materials. Ammonium chloride (10-g. portions), slaked lime 
(20-g. portions), concentrated hydrochloric acid, red litmus solu- 
tion, splints, red litmus paper, and blue litmus paper. 

Apparatus. Large test tube, one-hole rubber stopper, long el- 
bow, 4 gas bottles dry, 2500-cc. beaker, cover glasses. 

A. Preparation of Ammonia. 

1. Obtain 10 grams of ammonium chloride and 20 grams of 
calcium hydroxide (slaked lime). Smell of each. Has 
either an odor ? Now mix them well on a paper with a stir- 
ring rod and smell again. What is the odor? Put the 
mixture in the large test tube. Insert the one-hole stopper 
with the long elbow. Clamp the test tube in the ring stand, 
with the outlet tube turned up. Heat the test tube gently. 
Collect three bottles of the gas by inverting the bottle over 
the tube and holding it there until a drop of hydrochloric 
acid held on a stirring rod at the mouth of the bottle fumes 
strongly. Is ammonia heavier or lighter than air? Write 
the word-and-symbol equation for the reaction that takes 
place in the preparation of ammonia. 

2. Turn the outlet tube down and insert it into a bottle 
containing about 20 cc. of water. The tube must not touch the 
ivater. Why? Heat the mixture until no more gas is given 
off. (While heating, test the properties of the gas collected.) 

B. Properties of Ammonia. 

1. What is the color and odor of ammonia? 

2. Moisten your finger and hold it in the gas. Touch it 
to the tongue. What is the taste of ammonia ? 



GENERAL PROPERTIES OF ACIDS, BASES, AND SALTS 41 

3. Fill your large beaker with water and color it with a 
few drops of red litmus solution. Uncover a bottle of am- 
monia and quickly thrust its mouth into the water. Hold 
it in this position for five minutes. Result? Why not 
collect ammonia over water? 

4. Put a few drops of hydrochloric acid in a bottle ; cover 
and shake well. Place it mouth downward over a bottle 
of ammonia and remove the glass covers. Result? Explain 
and write the equation. 

5. Thrust a lighted splint into a bottle of ammonia. 
Does it burn or support combustion ? 

6. Remove the outlet tube from the bottle containing the 
liquid. Smell the liquid. Test it with red and with blue 
litmus. The gas ammonia combined with the water to 
form ammonium hydroxide. 

NH 3 +H 2 — > NH 4 OH 

For what purpose is this liquid used in the home? It is 
commonly called "ammonia." Is this correct? Explain. 

V. ACIDS, BASES, AND SALTS 

EXPERIMENT 20 

General Properties of Acids, Bases, and Salts 

Materials. Sulfuric acid, hydrochloric acid, nitric acid, acetic 
acid, crystals of tartaric acid, red litmus paper, blue litmus 
paper, magnesium ribbon pieces 1 cm. long, sodium hydroxide, 
potassium hydroxide, ammonium hydroxide, calcium hydroxide 
solution (limewater), sodium chloride, potassium sulfate, am- 
monium chloride, sodium carbonate, phenolphthalein, methyl 
orange. 

Apparatus. Test tubes, stirring rod, splints. 



42 ACIDS, BASES, AND SALTS 

A. General Properties of Acids. 

1. Half fill five clean test tubes with water. To the first 
add 3 drops of concentrated sulfuric acid, H2SO4; to the 
second add 3 drops of hydrochloric acid, HC1 ; to the third 
add 3 drops of nitric acid, HNO3 ; to the fourth add 3 drops 
of acetic acid, HC2H3O2 ; in the fifth dissolve a crystal of 
tartaric acid, H 2 C4H 4 6 . 

2. Dip the clean stirring rod into the dilute sulfuric acid 
and carefully taste a drop of it. Rinse the mouth with 
water after tasting. Wash the rod and dip it into the dilute 
solution of hydrochloric acid and taste a drop of it. Repeat, 
using nitric, acetic, and tartaric acids. What is the charac- 
teristic taste of acids ? 

3. In each tube place a very small piece of red and of blue 
litmus paper. What effect have acids on litmus? Empty 
the tubes and prepare solutions of the acids as in (1). To 
each tube add a drop of methyl orange. Note result in each 
case. 

Note: Litmus and methyl orange are called indicators because by their 
characteristic color reactions they indicate the presence of acids. By giving 
a different color they may also be used to indicate the presence of bases, as 
will be shown later. 

4. Place about 10 cc. of each acid in separate clean test 
tubes and add to each (one at a time) a piece of magnesium 
ribbon about 2 cm. long. Cover the tube with the hand, or a 
piece of cardboard, for about a minute or until effervescence 
ceases ; then test the gas in the tube with a burning splint. 
What is the gas? W T here does it come from? Write the 
word-and-symbol equations for the reactions that take place 
in each case. Do acids dissolve other metals? 

5. Write in a vertical column, one under the other, the 
names and formulas of the five acids you have studied. 



GENERAL PROPERTIES OF ACIDS, BASES, AND SALTS 43 

Compare the formulas. In what respect are the acids 
similar in composition ? 

6. Define an acid as completely as you can. 

7. What are the chief acids formed in vinegar ? lemon 
juice ? sour milk ? (See textbook.) 

B. General Properties of Bases. 

Note to student: An hydroxide (sometimes called hydrate) is composed 
of a metal or metallic radical combined with one or more hydroxyl radicals. 
Most of the hydroxides are insoluble. A few are soluble ; these are called 
bases and they possess properties in common, as will be noted below. 

1. In four different test tubes obtain 10 cc. of sodium 
hydroxide, NaOH, potassium hydroxide, KOH, ammonium 
hydroxide, NH 4 OH, and calcium hydroxide, Ca(OH) 2 , re- 
spectively. Label the tubes. 

2. Taste the calcium hydroxide. Do not taste the others 
without diluting greatly — about one drop in a half test tube 
of water. Describe the taste of the bases. 

3. Drop a small piece of pink and of blue litmus in each 
tube. Results? Test fresh solutions of each with a drop 
of methyl orange. Result in each case? Test fresh solu- 
tions of each w T ith a drop of phenolphthalein. Result in 
each case ? 

4. Rub a little of each solution between the fingers. 
Describe the feeling. 

5. Write in a vertical column, one under the other, the 
names and formulas of the four bases you have studied. 
Compare the formulas. In what respect are the bases similar 
in composition ? 

6. Define a base as completely as you can. 

7. What is the chief hydroxide in "limewater" ? "house- 
hold ammonia" ? "Red Seal lye" ? 



44 ACIDS, BASES, AND SALTS 

C. General Properties of Salts. 

1. In separate test tubes obtain about one gram of sodium 
chloride, NaCl, potassium sulfate, K2SO4, ammonium chlo- 
ride, NH4CI, and sodium carbonate, Na 2 C03. Label the tubes. 

2. Half fill the tubes with water ; shake and warm until 
the salts dissolve. Taste each solution. Do they taste like 
acids or bases ? Rinse your mouth. 

3. Place in each tube a piece of red and of blue litmus 
paper. 

What effect have salts such as sodium chloride and potas- 
sium sulfate upon litmus? 

Explain briefly why solutions of salts such as ammonium 
chloride turn litmus red. (See hydrolysis in text.) Why 
do solutions of salts like sodium carbonate turn litmus blue ? 

4. Rub a solution of each salt between the fingers. Do 
they feel slippery ? 

5. Write the names and formulas of the salts in a vertical 
column, one under the other. Compare the formulas. 

6. Define a salt as completely as you can. 

7. What is ordinary "table salt"? "baking soda"? 
"washing soda"? "saltpeter"? 

D. Litmus Reaction of Common Substances. 
* Note : These tests are to be made at home. 

1. Take home five or six strips of red and of blue litmus 
paper and test the following substances with a portion of 
each strip. Dissolve solids in water before testing. Tabu- 
late the reaction toward litmus under the following heads : 

Acid Reaction Basic Reaction Neutral Reaction 

Test: Borax, soap, faucet water, tooth powder, pickle, cream of tartar, 
washing soda, sour milk, sweet milk, vinegar, lemon juice, ripe fruits, green 
fruits, sugar, and olive oil. 



METHODS OF FORMING ACIDS, HYDROXIDES, AND SALTS 45 

EXPERIMENT 21 

Methods of Forming Acids, Hydroxides, and Salts 

Note: Two double laboratory periods will probably be required for this 
experiment. 

Materials. Sodium, filter paper, solution of phenolphthalein, 
lime, copper sulfate, ferric chloride and magnesium chloride 
(solution), sodium hydroxide, hydrochloric acid, magnesium 
ribbon, red phosphorus, sulfur, sodium chloride. 

Apparatus. Evaporating dish, glass plate, red litmus paper, blue 
litmus paper, small beaker, funnel, asbestos paper. 

A. Methods of Forming Acids. 

1. Action of non-metallic oxides on water. 

Note: A non-metallic oxide which when dissolved in water will produce 
an acid is called an acid anhydrid. 

(a) In the combustion spoon place a small piece of asbestos 
paper and on it a little sulfur. Ignite the sulfur in the 
Bunsen flame and lower the spoon into a bottle of air, cover- 
ing the bottle as far as possible with a glass plate. When 
the action ceases, remove the spoon. What is in the bottle ? 
Write the word-and-symbol equation for the reaction. 

Now add about 5 cc. of water and shake thoroughly. 
Test the liquid with both red and blue litmus. Result? 

What acid has been formed ? Write the word-and-symbol 
equation. 

(b) Reline the spoon with asbestos and repeat (a) , using 
a small amount of red phosphorus (about the size of a ker- 
nel of wheat). What is the oxide formed? Write the 
word-and-symbol equation. Add water; shake and test 
with litmus. Result? What is the acid formed? Write 
the word-and-symbol equation. 



46 ACIDS, BASES, AND SALTS 

(c) When carbon dioxide is dissolved in water, carbonic 
acid is formed. Write the word-and-symbol equation to 
show the reaction. 

(d) What oxide is the anhydrid of sulfuric acid? Write 
the word-and-symbol equation. 

2. Action of an acid with a higher boiling point on the 
salt of the acid desired. 

Note : Sulfuric acid has a much higher boiling point than the common acids, 
such as hydrochloric, nitric, and acetic acids, so that it is generally used in the 
preparation of these acids on a large scale. 

(a) Place about 5 grains of sodium chloride in a test tube 
and add 5 cc. of concentrated sulfuric acid. Warm gently 
and cautiously. Note the odor of the gas evolved. Test the 
gas with strips of red and of blue litmus moistened. Result ? 
This gas is hydrogen chloride or hydrochloric acid gas. 
Write the word-and-symbol equation for the reaction. 

Note: This method will be given in detail later. See Experiment 22. 

(6) Write the word-and-symbol equation for the reaction 
between sodium nitrate and sulfuric acid to form nitric acid. 

B. Methods of Forming Hydroxides. 

1. Action of metallic oxides on water. 

Note : A metallic oxide which when dissolved in water will produce a base 
is called a base anhydrid. 

(a) What is lime ? How is it formed ? 

(b) Obtain about 5 grams of lime. Place it in your 
small beaker and add 10 cc. of water. Stir for about 5 min- 
utes, then filter. What is the residue on the filter paper? 
What is in the filtrate ? Write a word-and-symbol equation 
to show what is formed when calcium oxide is added to water. 
Rub some of the solution between the fingers. Taste it. 



METHODS OF FORMING ACIDS, HYDROXIDES, AND SALTS 47 

Test it with litmus and phenolphthalein. Note results in 
each case. Write the word-and-symbol equation for the 
reaction. Is calcium hydroxide as soluble as sodium hy- 
droxide ? 

2. Action of metals on water. (Instructor's Experiment.) 

(a) Place on a piece of filter paper a piece of sodium about 
as large as a pea. Half fill your evaporation dish with 
water. Have a glass plate ready to cover it. Drop the 
sodium on the water and cover the dish with the glass plate. 
Note what takes place. (Recall Experiment 10.) 

When the action is over, rub some of the solution between 
the fingers. Result? Taste it carefully. Result? Test 
with pieces of red and of blue litmus. Result? Add a drop 
of phenolphthalein solution. Result? 

What substance is contained in the water ? 

Write a word-and-symbol equation to show its formation 
from the sodium and water. 

(b) Potassium hydroxide could be prepared in the same 
way, using potassium instead of sodium. Write the word- 
and-symbol equation to show what would take place. 

Are potassium and sodium hydroxides soluble or insoluble ? 

3. Insoluble hydroxides. 

In three separate test tubes obtain 5 cc. of solutions of 
the salts, copper sulfate, ferric chloride, and magnesium 
chloride. Fill each test tube half full of water and add 1 cc. 
of sodium hydroxide to each tube. What is formed in each 
case? Write the word-and-symbol equation to show what 
was formed in each case. 

Insoluble hydroxides do not feel slippery. They have no 
taste. They do not affect litmus. They do react with 
acids to form salts as soluble hydroxides do. 



48 ACIDS, BASES, AND SALTS 

C. Methods of Forming Salts. 

1. By neutralization — the action of an acid on a base. 
Place 10 cc. of sodium hydroxide, NaOH, in a beaker and 

add a drop of phenolphthalein. Then add hydrochloric 
acid, HC1, till the color just disappears. Rub some of the 
solution between the fingers. Taste it. Test it also with 
red and with blue litmus. Is an acid present? Is a base 
present? What has been formed? Evaporate 10 cc. of 
the solution to dryness in the evaporation dish. Taste the 
solid. Why is this process called neutralization? Write 
the word-and-symbol equation. 

2. By the action of acids on metals. 

Recall the action of sulfuric acid, H 2 S0 4 , on zinc in the 
preparation of hydrogen in Experiment 9. Write the word- 
and-symbol equation for the reaction. 

Add some hydrochloric acid, HC1, to about an inch of 
magnesium ribbon in a test tube. What gas is liberated? 
When the action ceases, evaporate some of the liquid to dry- 
ness. What salt was formed? Write the word-and-symbol 
equation for the reaction. 

Note: The instructor may perform the following experiments or merely 
discuss them in class. 

3. By the action between elements. 

When iron is heated with sulfur, iron sulfide, FeS, is formed. 

Write the word-and-symbol equation. 

Also when copper reacts with chlorine, copper chloride, 
CuCl 2 , is formed. 

Write the word-and-symbol equation. 

When zinc dust (2 parts) and sulfur (1 part) are mixed and 
heated, zinc sulfide, ZnS, is formed. 

4. By the action of acids on oxides. 



SOLUTIONS THAT CONDUCT THE ELECTRIC CURRENT 49 

Magnesium oxide, MgO, reacts with hydrochloric acid, HC1, 
to form magnesium chloride, MgCl 2 , and water. 
Write the word-and-symbol equation. 

5. From another salt when a gas is formed. 

The salt potassium chlorate, KC10 3 , when heated will 
give a new salt, potassium chloride, KG, and oxygen. 
Write the word-and-symbol equation. 

6. From another salt when an insoluble substance is 
formed. 

If a solution of the salt barium chloride, BaCl 2 , is added to 
a solution of sodium sulfate, Na2S04, two new salts are formed 
— one insoluble salt, barium sulfate, BaSC>4, and one soluble 
salt, sodium chloride, NaCl. 

Write the word-and-symbol equation. 

EXPERIMENT 22 

(Class Experiment) 

Solutions That Conduct the Electric Current 

Materials. An electric lighting current, distilled water, about 
half normal solutions of hydrochloric acid and sulfuric acid and 
acetic acid, sodium hydroxide, ammonium hydroxide, sodium 
chloride, zinc sulfate, sugar, alcohol, concentrated sulfuric acid. 

Apparatus. A lamp block with a 16 candle-power lamp, an 

electric cell consisting of a tall 10-cc. beaker and 2 platinum 

or carbon electrodes. 

Note: If the solution of a substance in water will conduct the electric 
current, the substance is called an electrolyte. 

If it will not conduct a current it is a non-electrolyte. 

A. Conducting Power of Pure Water. 

1. Connect an electric lighting current in series with a 16 

candle-power electric lamp and cell consisting of a small beaker 



50 ACIDS, BASES, AND SALTS 

and two carbon electrodes. The lamp cuts down the current 
strength and indicates the passing of a current by lighting. 

2. Pour distilled water into the beaker until the electrodes 
are completely immersed. Does the lamp glow? Will 
pure water conduct the electric current ? 

B. Conducting Power of Concentrated Sulfuric Acid. 

1. Immerse perfectly dry electrodes in a cell of concen- 
trated sulfuric acid. Does the lamp glow? Will pure 
concentrated sulfuric acid conduct the electric current? 

C. Conducting Power of Solutions of Acids. 

1. Dissolve one drop of sulfuric acid in the distilled water 
in the cell. Does the lamp glow? Will a water solution 
of sulfuric acid conduct the electric current? Is sulfuric 
acid an electrolyte ? 

2. Remove and wash the electrodes and replace the solu- 
tion of sulfuric acid with a dilute solution of hydrochloric 
acid. Result ? 

3. Remove and wash the electrodes and replace solution 
of hydrochloric acid with a solution of acetic acid. Does the 
lamp glow as brightly as in (1) or (2)? Does the acetic 
acid conduct the current as well as hydrochloric acid ? The 
action of these acids is characteristic of nearly all acids. 
Acids in water give ions. The ions carry the current. What 
ions does sulfuric acid give? What ions does hydrochloric 
acid give? What ions does acetic acid give? What ions 
do all acids give? Some substances in solution give more 
ions than others. The one that gives the most ions conducts 
the current best. The acid that gives the most hydrogen 
ions is the strongest acid (the concentrations being the same) . 

Which of the three acids above are strong? which weak? 



SOLUTIONS THAT CONDUCT THE ELECTRIC CURRENT 51 

D. Conducting Power of Solutions of Bases. 

1. Replace the acid solution by a solution of sodium hy- 
droxide. Result? Is sodium hydroxide an electrolyte? 

2. Repeat, using ammonium hydroxide. Does the lamp 
glow as brightly as (1) ? Does ammoni m hydroxide con- 
duct the current as well as a solution of sodium hydroxide? 

What ions does sodium hydroxide give ? 

What ions does ammonium hydroxide give ? 

What ions are common to all bases? 

The base giving most hydroxyl ions is the strongest (the 
concentrations being the same in each case) . Which is the 
stronger base, sodium hydroxide or ammonium hydroxide ? 

E. Conducting Power of Solutions of Salts. 

1. Place in the beaker a solution of sodium chloride. 
Result? What ions does sodium chloride give in solution? 

2. Repeat, using a solution of zinc sulfate. Result? 
What ions does zinc sulfate give in solution? In general, 
what ions do all the more common salts give in solution ? 

F. Conducting Power of Non-electrolytes. 

1. Place in the beaker a solution of sugar. Does it con- 
duct the electric current ? Why ? 

2. Repeat, using a solution of alcohol. Does it conduct 
the current ? Why ? 

Questions 

1 . What electrolytes did you study in this experiment ? 

2. What non-electrolytes did you study? 

3. Define an acid, a base, and a salt with reference to the 
ions they give in solution. 

4. Define a strong acid. 

5. Define a concentrated acid. 



52 THE HALOGENS AND HYDROCHLORIC ACID 

VI. THE HALOGENS AND HYDROCHLORIC ACID 

EXPERIMENT 23 
Chlorine, Bromine, and Iodine 

Materials. Bleaching powder (fresh), 4 7V sulfuric acid, strips 
of colored calico, white cloth, colored flowers, potassium iodide, 
potassium bromide, starch paste, and alcohol. 

Apparatus. 500-cc. Florence flask, stopper, thistle tube, de- 
livery tubes, gas bottles, 250-cc. Florence flask, test tubes, and 
beaker. 

Caution: Chlorine is poisonous. The instructor usually performs the 
experiment. 

A. Preparation of Chlorine. 

1. Place 50 grams of bleaching powder (chlorinated lime) 
in a 500 cc. Florence flask. To the flask fit a stopper 
containing a thistle tube and a delivery tube. The delivery 
tube should extend to the bottom of a dry bottle covered 
with cardboard. The gas is heavier than air and may be 
collected by displacement of air. 

Through the thistle tube add about 50 cc. of 4 N sulfuric 
acid. If necessary, warm the flask gently. Collect four 
bottles of the gas and cover them with glass plates. Com- 
plete the equation, naming the substances : 

CaOCl 2 +H 2 S0 4 ^ 

B. Properties of Chlorine. 

1. Extend the delivery tube into the bottle half filled 
with water. Does chlorine dissolve in water ? 

2. Note the color of chlorine gas, and very carefully note 
its odor by wafting to the nose by the hand. 

3. In another bottle suspend a strip of moist calico and 
a strip of dry, colored calico. Explain the water's action. 



CHLORINE, BROMINE, AND IODINE 53 

4. In another bottle place violets or a carnation. Re- 
sult? 

5. In the fourth bottle suspend a strip of moist white 
cloth having an ink stain. Result ? 

6. Into the "chlorine water" prepared in (1) place a 
strip of white goods having an ink stain. 

7. Explain the use of bleaching powder (chlorinated lime) 
in removing stains and in bleaching goods, and as a disin- 
fectant. 

C. Preparation and Properties of Bromine. 

1. Place 5 grams of powdered potassium bromide and 3 
grams of manganese dioxide in a 250 cc. Florence flask. Add 
20 cc. of 4 N sulfuric acid. Warm if necessary. Write the 
equation for the preparation. 

2. Note the color and the odor of the bromine gas. At 
an ordinary temperature bromine is a liquid. It is the 
only liquid non-metal. Examine some liquid bromine. 
Pour a drop of bromine into water. Does it dissolve ? Is it 
heavier or lighter than water ? 

D. Preparation and Properties of Iodine. 

1. Repeat C, 1 using potassium iodide instead of potas- 
sium bromide. Write the equation for the preparation of 
iodine. 

2. Note the color of iodine vapor. What collects upon 
the cold neck of the flask ? 

3. Examine crystals of iodine. Describe them. Put a 
crystal in a test tube and heat it. Result? What collects 
on the sides of the tube? Explain. 

4. Try to dissolve a crystal of iodine in water. Result? 
Pour off the water and add alcohol. The solution of iodine 



54 THE HALOGENS AND HYDROCHLORIC ACID 

in alcohol is called "tincture of iodine." What is this used 
for? 

5. To a beaker of water add 1 drop of starch paste and then 
1 drop of the tincture of iodine prepared in (4). Result? 
This is a test for starch. 



EXPERIMENT 24 
Preparation and Properties of Hydrochloric Acid, HC1 

Materials. 30 g. portions of NaCl, 4 N sulfuric acid, litmus 
paper, splints, blue litmus solution, silver nitrate solution, am- 
monium hydroxide, nitric acid, potassium chloride. 

Apparatus. 250 cc. Florence flask, delivery tubes, gas bottles, 
large beaker, test tubes, thistle tube. 

A. Preparation of the Gas Hydrogen Chloride. 

1. Put about 30 grams of sodium chloride (common salt) 
into your 250 cc. Florence flask. Insert the 2-hole rubber 
stopper containing the thistle tube and delivery tube. At- 
tach the long delivery tube to the short one and extend it 
into a dry gas bottle covered with cardboard. Add through 
the thistle tube about 50 cc. of sulfuric acid and warm 
gently. Collect 2 bottles of gas hydrogen chloride. The 
bottles are full when a piece of moist blue litmus paper held 
at the mouth turns pink. Cover them with about 50 cc. 
of water, forming hydrochloric acid. Write the word-and- 
symbol equation for the preparation of the gas hydrogen 
chloride. 

B. Properties of the Gas Hydrogen Chloride. 

1. Note the color and odor of the gas. Is it heavier than 
air? 



SULFUR AND COMPOUNDS OF SULFUR 55 

2. Thrust a lighted splint into one of the bottles. Does 
hydrogen chloride burn ? Does it support combustion ? 

3. Fill your large beaker with water and add 1 cc. of blue 
litmus solution. Uncover the second bottle of the gas and 
invert it quickly in the beaker of water. Explain the result. 
C. Properties of Hydrochloric Acid. 

1. Remove the delivery tube from the bottle containing 
the water in which the hydrogen chloride has dissolved, 
forming hydrochloric acid. Test the liquid with blue litmus 
paper. Result? Taste a drop of the liquid. Result? 
What is the hydrochloric acid on your desk ? 

2. Place 5 cc. of the hydrochloric acid which you prepared 
in a test tube and add a drop of silver nitrate. What is the 
white precipitate formed ? Write the word-and-symbol equa- 
tion. Divide the precipitate into two parts. To one part 
add ammonium hydroxide till the liquid is alkaline. Result ? 
To the other part add nitric acid. Result ? 

3. Repeat (2), using any soluble chloride instead of hy- 
drochloric acid. Result? Write the equation to show the 
formation of silver chloride. 

State the test for hydrochloric acid and its salts. What 
is the general method for the preparation of an acid? 

VII. SULFUR AND COMPOUNDS OF SULFUR 
EXPERIMENT 25 

Sulfur and Compounds of Sulfur 

Materials. Sulfur, colored goods, a colored flower, sodium 

sulfite, concentrated sulfuric acid. 
Apparatus. Deflagrating spoons, gas bottle, pneumatic trough, 

litmus paper, flask, test tubes, safety tube, delivery tube. 



56 SULFUR AND COMPOUNDS OF SULFUR 

A. Sulfur. 

1. Note the physical properties of sulfur, i.e. color, odor, 
taste. 

2. Boil some sulfur in a test tube half full of water. Filter 
and note that the water is pale yellow. Is sulfur soluble 
in water? 

3. What are some of the uses of sulfur? 

B. Sulfur Dioxide, S0 2 . 

1. Place about 20 grams of sodium sulfite in a flask. In- 
sert the stopper with a thistle tube and delivery tube. Add 
concentrated sulfuric acid through the thistle tube. Warm 
the flask if necessary. Collect the gas by downward dis- 
placement of air. Fill 3 bottles. Write the equation to 
show the reaction that takes place in this method of prepar- 
ing sulfur dioxide. 

Note: Sulfur dioxide can also be prepared by burning sulfur in the air. 
Write the equation. 

2. Note the physical properties of the gas, i.e. the color 
and odor. Half fill your trough with water and quickly 
invert one bottle of sulfur dioxide in it. Is sulfur dioxide 
soluble in water? When the water no longer rises slip a 
glass plate over the mouth of the bottle and place it right 
side up on the table. Taste the liquid in the bottle. Test 
it with red and with blue litmus. What is formed when sulfur 
dioxide dissolves in water ? Write the equation to show the 
reaction. 

3. Into the second bottle thrust a burning splint. Does 
sulfur dioxide burn or support combustion ? 

4. Into the third bottle of sulfur dioxide place a strip of 
moistened colored goods and also a fresh violet or carnation 



SULFURIC ACID AND HYDROGEN SULFIDE 57 

or other colored flower. This illustrates the use of sulfur 
dioxide as a bleaching agent for nuts and fruits before they 
are dried. In this case the sulfur dioxide is prepared by 
burning sulfur in air. 

EXPERIMENT 26 
Sulfuric Acid and Hydrogen Sulfide 

Materials. Pine splint, concentrated sulfuric acid, sugar, sodium 
acetate, distilled water, barium chloride solution, hydrochloric 
acid, and ferrous sulfide. 

Apparatus. Test tubes, flask, delivery tube, safety tube, litmus 
paper, and splints. 

A. Sulfuric Acid. 

1. Pour 1 cc. of concentrated sulfuric acid into 5 cc. of 
water in a test tube. {Caution: Never pour the water into 
the acid.) Note the heat produced by touching the bot- 
tom of the test tube to the hand. 

2. Thrust a pine splint into 5 cc. of concentrated sulfuric 
acid in a test tube. Warm gently. Remove the splint and 
note result. 

3. To a gram of sugar in another test tube add a few drops 
of concentrated sulfuric acid. Warm and explain result. 
Write the equation to illustrate in a general way what took 
place. Explain why concentrated sulfuric acid causes such 
serious burns. 

4. Half fill a test tube with distilled water , then add a drop 
of concentrated sulfuric acid. To this add 1 cc. of barium 
chloride solution. The precipitate is barium sulfate, BaS0 4 . 
Try to dissolve the precipitate in hydrochloric acid. Result 9 
In nitric acid. Result? State the test in your own 



58 SULFUR AND COMPOUNDS OF SULFUR 

words. Complete the following equations, naming all sub- 
stances : 

H 2 S0 4 +BaCl 2 — ^ 

Na 2 S0 4 +BaCl 2 — ^ 
B. Hydrogen Sulfide. 

1. Set up your flask as a gas generator. In it place 10 
grams of ferrous sulfide. Add hydrochloric acid through the 
safety tube. Collect a bottle of the gas by downward dis- 
placement of air. Complete the following equation for 
the reaction, naming all substances : 

FeS+2 HC1— ^ 

2. Note the physical properties of the gas, i.e. color, odor. 

Note : Let the gas bubble into a test tube of water while you are studying 
the properties of the gas in the bottle. 

3. Thrust a burning splint into the bottle of gas collected. 
Result? 

The hydrogen sulfide is oxidized to water and sulfur 
dioxide when it burns. Write the equation for the reaction 
which takes place when hydrogen sulfide burns in the air. 

2H 2 S+3 2 — ^ 

Sometimes sulfur is precipitated if the oxidation is incom- 
plete. Write an equation to illustrate this reaction. 

2H 2 S+0 2 -> 

Hydrogen sulfide is a strong reducing agent. 

4. Test the solution of hydrogen sulfide prepared in (2) 
with red and with blue litmus. Result? It is a very weak 
acid. Put a drop of the solution on a silver coin. Result? 
Why do silver spoons turn black if used for eating eggs ? 

5. How would you test for a sulfide ? 



CARBON 59 

VIII. CARBON. CARBON DIOXIDE. FLAMES 

EXPERIMENT 27 
Carbon 

Materials. Potato, bread, meat, starch, sugar, cotton, paper, 
wood, coal, any vegetable, sand, wood charcoal, lampblack, 
bone black, graphite, coal, sulfuric acid, sodium hydroxide, 
brown sugar, copper oxide. 

Apparatus. Iron pan, ring stand, test tubes, filter paper, funnel, 
beaker, hard-glass test tube. 

A. Occurrence of Carbon. 

1. Place a thin layer of sand in a small iron pan and on it 
put small pieces of the substances listed above. Cover the 
materials with sand to protect from the action of the air. 
Why? Heat until smoking ceases. Cool and examine. 
What has happened to the substances? What is the black 
residue ? 

How is willow charcoal prepared ? How is animal charcoal 
prepared ? For what purposes are these substances used ? 

2. Close the holes in the Bunsen burner ; light it and turn 
it low. This makes a small luminous flame. Hold a cold, 
dry surface or evaporating dish in this flame. Result? 
What is this form of carbon called ? 

How is lampblack prepared? For what purpose is it 
used? What element is found in the foods we eat and the 
fuels we burn ? 

B. Properties of Carbon. 

1. In five different test tubes place respectively about 
5 grams of wood charcoal, bone black (animal charcoal), 
graphite, lampblack, coal. 



60 CARBON. CARBON DIOXIDE. FLAMES 

Note the physical properties of each. 
Place small portions of each in other test tubes and add 
some water. Are any of the forms of carbon soluble in water ? 

2. Place portions of each in other tubes and add some 
sulfuric acid or any acid. Result ? 

Repeat, using sodium hydroxide. Result? 

3. Dissolve 20 grams of brown sugar in 100 cc. of water. 
Note the color of the solution. Add 10 grams of bone black 
and boil for ten minutes. Filter. Note the color of the fil- 
trate. Taste it. Where is the sugar? If the filtrate is not 
colorless, add some more bone black ; warm and filter again 
till it is colorless. How is bone black used in sugar refining ? 

4. In a hard-glass test tube heat for 10 minutes a mixture of 
3 grams of powdered wood charcoal with 3 grams of copper 
oxide. Cool and pour the contents upon a paper. What is 
the reddish material ? What becomes of the charcoal ? 

Write an equation to show the reducing action of carbon 
in this case. 

EXPERIMENT 28 

Carbon Dioxide, C0 2 

Materials. Marble chips, dilute hydrochloric acid, splints, lime- 
water. 

Apparatus. Flask, safety tube, stopper, delivery tube, bottles, 
beaker, test tubes. 

A. Preparation of Carbon Dioxide. 

1. Place some pieces of marble in your 250 cc. flask. Insert 
the stopper containing the safety tube and the delivery tube. 
Add dilute hydrochloric acid through the safety tube, a few 
centimeters at a time. 

2. Collect three bottles of the gas by downward displace- 



CARBON DIOXIDE, C0 2 61 

ment of air. The bottle is full when the flame of a burning 
splint held at its mouth is extinguished. 

3. Write the equation for the reaction between hydro- 
chloric acid and marble in the preparation of carbon 
dioxide. 

B. Properties of Carbon Dioxide. 

1. Note the chief physical properties of carbon dioxide. 
Test its solubility in water by inserting one of the bottles of 
the gas in a beaker of water. Let it stand. Does the water 
rise? Is carbon dioxide soluble in water? 

2. Into a second bottle of the gas thrust a burning splint. 
Result ? What use does this suggest for the gas ? 

3. Prove that the gas is heavier than air by pouring a 
bottle of it into an empty bottle as if it were a liquid. Test 
for its presence in the second bottle with the burning splint. 
Result? 

4. Extend the delivery tube from the generator into 10 cc. 
of limewater in a test tube and allow the carbon dioxide 
to bubble through the limewater. What is the white precipi- 
tate obtained? Write the equation for the reaction. This 
is a test for carbon dioxide. 

5. Prove that air exhaled from the lungs contains carbon 
dioxide by blowing some air through 10 cc. of fresh lime- 
water in a test tube. Explain the presence of carbon dioxide 
in the air exhaled from the lungs. 

6. Burn a splint in a bottle. Cover the bottle. Add 
limewater and shake. Result? Explain. 

7. Burn a piece of paper in a bottle. Cover the bottle. 
Add limewater and shake. Result? Explain. 

8. Any substance which contains carbon will form carbon 



62 CARBON. CARBON DIOXIDE. FLAMES 

dioxide when it burns. The limewater test for carbon 
dioxide is therefore an indirect test for carbon. 

Note: If there is time, perform A, i and B, i of Experiment 29. 

EXPERIMENT 29 
Carbonic Acid and Carbonates 

Materials. Carbon dioxide generator, sodium hydroxide, sodium 
bicarbonate, copper carbonate, magnesium carbonate, sodium 
bicarbonate, hydrochloric or sulfuric acids, limewater, baking 
soda, washing soda, boiler scale, sea shells, limestone. 

Apparatus. Evaporating dish, test tubes. 

A. Carbonic Acid, H 2 C0 3 . 

1. Pass some of the carbon dioxide gas from the generator 
used in Experiment 28 through 25 cc. of water. The gas 
combines with the water to form carbonic acid. Write the 
equation for the reaction. Taste the liquid. Result ? Test 
the acid formed with blue litmus paper. Result? 

Now explain what soda water is. 

B. Salts of Carbonic Acid, the Carbonates. 

1 . Pass carbon dioxide through 20 cc. of solution of sodium 
hydroxide in a test tube as long as any gas is absorbed. Pour 
the solution into your evaporating dish and evaporate to 
dryness. What substance remains? Write the equation 
for the reaction. 

2. In labeled tubes obtain 1 gram of sodium bicarbonate, 
copper carbonate, magnesium carbonate, and sodium carbon- 
ate. Note the physical properties of each. Place half of the 
sodium bicarbonate in another test tube, add 20 cc. of water, 
warm, and shake. Is sodium bicarbonate soluble in water? 

In like manner test the solubilitv of the other carbonates 



FLAMES 63 

you obtained. Make a table showing which of the carbon- 
ates tested are soluble in water and which are insoluble. 

3. To the other half of the sodium bicarbonate add either 
dilute hydrochloric or sulfuric acid. Carbon dioxide gas is 
evolved. Prove this by holding a drop of limewater on a 
stirring rod in the gas coming from the tube. If the drop 
becomes milky, carbon dioxide is indicated. 

Write the equation for the reaction. 

In like manner test the action of an acid on the other car- 
bonates you obtained. Write the equations for the reactions 
in each case. All carbonates, when treated with hydro- 
chloric or sulfuric acid, evolve carbon dioxide. This is the 
test for a carbonate. 

4. Test baking soda for a carbonate. What is baking soda ? 

5. Test washing soda for a carbonate. What is washing 
soda? 

6. Test boiler scale from a teakettle at home for a carbon- 
ate. What is boiler scale ? 

7. Test coral, oyster shell, or any other sea shell for a car- 
bonate. Of what are sea shells composed chiefly? 

8. Test limestone for a carbonate. What is limestone ? 

EXPERIMENT 30 

Flames 

Materials. Candles, splints, powdered wood charcoal. 
Apparatus. Glass elbow or tube, wire screen, evaporating dish. 

A. Candle Flame. 

1. Place a lighted candle so that the flame is against a 
black background and note the different cones in the flame. 
Draw a diagram showing the different parts of the flame. 



64 CARBON. CARBON DIOXIDE. FLAMES 

2. Test the different cones in the flame with a small splint. 
Which is the hottest cone ? 

3. Blow out the flame and hold a lighted splint in the little 
column of smoke coming from the wick. Explain the result. 

4. Candle wax is composed chiefly of carbon and hydrogen. 
What then are the chief products of combustion when a 
candle burns in the air? Prove the presence of these prod- 
ucts by very simple experiments. 

B. Bunsen Flame. 

1. Draw the diagram of a Bunsen flame. 

2. Test the different cones in the flame with small splints. 
Which is the hottest flame? Hold a splint horizontally in the 
base of the Bunsen flame for three seconds. Explain the 
result. 

3. Put one end of a glass elbow or glass tube in the inner 
cone just above the burner tube and light the gas at the end 
of the glass tube. Raise the tube until it is in the Bunsen 
flame's second cone. Result ? What is the inner cone of the 
Bunsen flame? 

4. Press the wire screen down in the Bunsen flame. Why 
does the flame not burn above the screen? Light the gas 
above the screen. Turn the gas off, then turn it on again 
and light it above the wire screen held about two inches 
above the top of the burner. Explain. 

5. Shake some powdered wood charcoal into a non-lumi- 
nous Bunsen flame. Explain the result. Beat some of the 
chalk dust from a blackboard eraser into a non-luminous 
flame. Explain the result. 

6. Make the Bunsen flame luminous by closing the holes 
in the tube. Hold a clean, dry evaporating dish in the 



FLAMES 65 

luminous flame. Why is carbon (lampblack) deposited? 
Will a non-luminous flame deposit soot? What makes a 
flame luminous ? 

7. The flame produced by the burner of the kitchen range 
is non-luminous. Explain how the burner is constructed to 
produce this non-luminous flame. Draw a diagram. 

What advantages has a non-luminous flame over a lumi- 
nous one in such a range ? How could the same gas that is 
used for lighting purposes in the range be used for lighting 
the home ? 



PART II 

SECOND TERM'S WORK 
IX. COMMON ORGANIC COMPOUNDS 

An organic compound is one that contains carbon. Or- 
ganic chemistry is the study of compounds containing car- 
bon. Carbon monoxide, carbon dioxide, carbonic acid, and 
the carbonates are organic compounds, but for the sake of 
convenience, and because of their common occurrence, they 
are usually studied in inorganic chemistry. 

The simplest organic compounds are composed of carbon, 
hydrogen, and oxygen. The more complex compounds 
found in plant and animal tissues are composed of carbon, 
hydrogen, oxygen, nitrogen, sulfur, and phosphorus in 
varying proportions. These complex bodies are usually 
decomposed when heated, leaving a black residue of car- 
bon. This is called a "charring test" for an organic 
compound. 

Some substances, like kerosene, when heated, burn leaving 
no residue of carbon. Such substances burn with a lumi- 
nous flame that deposits "soot," which is carbon, upon a cool 
surface. This is also a test for an organic substance. This 
is called the "soot test." 

66 



TESTS FOR ORGANIC COMPOUNDS 



67 



There are other substances, like alcohol and ether, which 
neither leave a residue nor deposit "soot" when they burn. 
If a drop of limewater is held over such a flame, the presence 
of carbon dioxide may be detected. This test holds good 
for any organic substance, for carbon dioxide is always formed 
when such a substance burns. 



EXPERIMENT 31 
Tests for Organic Compounds 

Materials. Flour, sugar, salt, baking powder, wood, milk, 
talcum powder, kerosene, gasoline, paraffine, turpentine, olive 
oil, lard, ether, limewater, alcohol. 

Apparatus. Bunsen burner, evaporating dish, test tubes, stirring 
rod. 

A. " Charring Test " for an Organic Compound. 

1. Heat about 2 grams of flour in an evaporating dish. 
Note the results. What remains? Heat the black residue 
strongly. Will it burn? Continue heating till the carbon 
has entirely disappeared. What is the white ash that re- 
mains? Does flour contain organic compounds? Does it 
contain inorganic compounds? Clean the dish with sapolio. 

2. In like manner heat a very small amount of sugar, salt, 
baking powder, wood, milk, talcum powder. Tabulate 
your results as follows : 



Organic Compounds 


Inorganic Compounds 


Organic and Inorganic 
Compounds 









68 COMMON ORGANIC COMPOUNDS 

B. " Soot Test " for Organic Compounds Which Do Not Char When 

Heated. 

1. Heat in a dry evaporating dish 1 cc. of kerosene until 
it burns. Is the flame colored? Hold a cold glass plate 
in the flame. Result ? What is the black deposit ? Is kero- 
sene an organic compound? Is there a residue? 

2. In like manner test gasoline, paraffine, turpentine, 
olive oil, and lard. State the result in each case. 

C. " Carbon Dioxide Test " for Organic Compounds. 

1. Heat 1 cc. of ether in an evaporating dish till it burns. 
Is the flame colored ? Hold a cold glass plate over the flame. 
Does it deposit " soot" ? Obtain 5 cc. of clear limewater in a 
clean test tube. Dip the stirring rod in the limewater and 
hold the clear drop over the flame. Does the drop become 
milky? Explain fully. 

2. In the same way test alcohol. Is it an organic com- 
pound? 

3. Mix 5 grams of sugar with 5 grams of powdered copper 
oxide. Place the mixture in a hard-glass test tube fitted with 
a delivery tube that dips into 10 cc. of limewater in another 
test tube. Heat the mixture. Note the drops of water on the 
cool upper portion of the test tube. Explain. Note the 
precipitate produced in the limewater. Explain. What is 
the reddish material in the test tube? Explain. The re- 
actions that take place are as follows : 

(1) C 12 H 22 O n +24 CuO — ^ 11 H 2 0+12 C0 2 +24 Cu 

(2) C0 2 +Ca(OH) 2 — ^ CaCQ 3 +H 2 Q 

The carbon dioxide test is the best test for carbon in a com- 
pound. 



HYDROCARBONS 69 

HYDROCARBONS 

The hydrocarbons are organic compounds composed of 
hydrogen and carbon. Methane CH 4 , ethane C 2 H 6 , and 
acetylene, C 2 H 2 , are the most common gaseous hydrocarbons. 
Gasoline, kerosene, benzene, and turpentine are liquid 
hydrocarbons. They contain a greater number of carbon 
and hydrogen atoms than do the gases. The solid hydro- 
carbons, like paraffine and vaseline, contain a still higher num- 
ber of carbon atoms. The gases burn readily. Illuminating 
and fuel gases usually contain one or more of them. The 
liquids are volatile and inflammable. They are good solvents 
for fats and waxes. 

Note: For further information concerning the hydrocarbons read almost 
any up-to-date elementary textbook on chemistry or a good organic chemistry 
such as Norris' " Organic Chemistry," or Stoddard's " Introduction to Organic 
Chemistry." 

EXPERIMENT 32 

Hydrocarbons 

Materials. Calcium carbide, gasoline, kerosene, lard or butter, 
paraffine candles, chloroform, benzene, carbon tetrachloride. 

Apparatus. Test tubes, test tube rack, evaporating dish, stirring 
rod. 

A. Composition of Hydrocarbons. 

1 . Explain how you would prove the presence of hydrogen 
in a substance. (See Experiment 12, A.) 

2. Explain how you would test for carbon a substance 
which does not char when heated. (See Experiment 31, 
B and C.) 

B. Some Common Gaseous Hydrocarbons. 

1. Light the gas from the Bunsen burner. Test for hydro- 
gen by the method explained above, i.e. hold a cold object 



70 COMMON ORGANIC COMPOUNDS 

above the flame and look for drops of water. Does illumi- 
nating gas contain hydrogen ? Now explain why a cold flat- 
iron or a teakettle filled with cold water becomes wet when 
first placed over a gas burner of the kitchen range. Make 
the flame colored by closing the hole in the burner. Apply 
the test for carbon given above, i.e. hold a cold object in the 
flame. Is "soot" deposited? Does illuminating gas con- 
tain carbon? Methane is the chief hydrocarbon in illumi- 
nating gas. What is its formula ? Write the equation, indi- 
cating the products formed when methane burns. 

2. Half fill a test tube with water and prepare to work 
rapidly. Stand it in the rack and drop into it a piece of cal- 
cium carbide about the size of a bean. Note the odor of the 
acetylene. Light the escaping gas. Describe the flame. 
How can the gas be used for lighting purposes ? The formula 
for acetylene is C 2 H 2 . Write the equation for the formation 
of acetylene from calcium carbide and water. Write the 
equation, indicating the products formed when acetylene 
burns in the air depositing much soot. With the proper kind 
of burner acetylene may be used for illuminating purposes. 
Enough air is admitted to completely burn the acetylene and 
no soot is formed. Write an equation for the complete 
combustion of acetylene. 

C. Some Common Liquid Hydrocarbons. 

1. Pour 1 cc. of gasoline into an evaporating dish and the 
same volume of kerosene into another. (Two students may 
perform this test together.) Note the time it takes each to 
evaporate. Which is the more volatile ? 

2. Test the inflammability of each hydrocarbon by dip- 
ping the end of the stirring rod into the liquid and then 



HYDROCARBONS 71 

bringing it to the tip, of the flame. Which substance is the 
most inflammable? Why should you be so careful in using 
gasoline near a flame ? 

3. Dissolve some fat, such as butter or lard, in kerosene and 
in gasoline. Which of these liquids is best to use in cleaning 
spots from clothing ? Why ? 

4. What is the source of gasoline and kerosene? 

5. Benzene has the formula C 6 H 6 . It is called an aro- 
matic hydrocarbon. Note its odor ; test its inflammability. 
What is the source of benzene? W T hat are some of the im- 
portant commercial products formed from benzene? 

D. Solid Hydrocarbons. 

1. Paraffine is a solid hydrocarbon. Obtain a paraffine 
candle, light it, and prove that it contains hydrogen and 
carbon. 

2. What is the source of paraffine? 

3. What is vaseline ? 

E. Chloroform and Carbon Tetrachloride. 

Part or all of the hydrogen atoms in methane, CH 4 , and in 
the other hydrocarbons may be replaced by different ele- 
ments and radicals. If one hydrogen atom in methane is 
replaced by chlorine, raowo-chlor-methane, CH3CI, is formed. 
If two are replaced, cZi-chlor-methane, CH2CI2, is formed. 
If three are replaced, ^n-chlor-methane, CHCI3, is formed ; 
this is chloroform. If four are replaced, ^ra-chlor-methane, 
CCU, is formed ; this is carbon tetrachloride. 

1. Obtain 5 cc. of chloroform. Note its odor. Place a 
drop on your hand. Is it volatile ? 

2. Dip the stirring rod into it and hold it in the flame. 
Is it inflammable ? 



72 COMMON ORGANIC COMPOUNDS 

3. Try to dissolve a drop of olive oil in it. Result? 

4. Chloroform is an anaesthetic and is a useful and safe 
cleansing agent, since it is non-inflammable. 

5. Obtain 5 cc. of carbon tetrachloride. Note its odor. 
Place a drop on your hand. Is it volatile ? 

6. By means of the stirring rod test its inflammability. 
Result? Pour some on a burning splint. Result? It is 
sold as "Pyrene" for extinguishing fires. 

7. Try to dissolve olive oil in it. Result? It is much 
used for cleansing purposes. It is the chief constituent of 
"Carbona." 

ALCOHOLS 

Alcohols are organic hydroxides. The hydrogen atoms 
in a hydrocarbon may be replaced by elements or radicals. 
If a hydrogen atom is replaced by a hydroxy 1 group, we have 
an alcohol. For example, the hydrocarbon methane has the 
formula CH4. Replace one hydrogen atom by the hydroxyl 
group OH and we have CH 3 OH, which is methyl alcohol, called 
wood alcohol. Similarly, the hydrocarbon ethane is C 2 H 6 . 
Remove one hydrogen atom and replace it by OH and we 
have C2H5OH, ethyl alcohol, called common alcohol or grain 
alcohol. These organic hydroxides, like the inorganic hydrox- 
ides, will combine with acids to form organic salts, called esters. 
In every other respect they are unlike inorganic hydroxides. 
Although the common alcohols are soluble in water, the 
solutions will not conduct an electric current or affect litmus 
or feel slippery. Methyl alcohol and ethyl alcohol are 
volatile, colorless liquids, having rather pleasant odors. 
They are good solvents, good disinfectants, and preserva- 
tives. 



SOME COMMON ALCOHOLS 73 

EXPERIMENT 33 
Some Common Alcohols 

Materials. Ethyl alcohol, methyl (wood) alcohol, litmus paper, 
camphor gum, iodine, a solution of iodine in potassium iodide, 
sodium hydroxide, patent medicine, ether, olive oil, carbolic 
acid, glycerin. 

Apparatus. Stirring rod, evaporating dish, test tubes. 

A. Properties of the Common Alcohols. 

1. What is the chemical name for common alcohol? 
Write its formula. What is the chemical name for wood 
alcohol ? Write its formula. 

2. Obtain 10 cc. of each liquid in two clean, dry test tubes. 
Note the odor of each. Describe the difference. 

3. Using a clean stirring rod, taste a drop of each. De- 
scribe the difference. 

Caution: Do not swallow the liquids — they are poisons. Methyl alcohol 
(wood alcohol) produces blindness and death. Ethyl alcohol is a " habit " 
producing drug, and produces death ultimately from slow poisoning. 

4. Test the solubility of each alcohol in water. 

5. Test them with strips of red and with blue litmus. 
Do alcohols affect litmus ? 

6. Pour 2 cc. of each alcohol in different evaporating 
dishes. Apply the flame to each until it burns. Note 
the color of the flame and the heat given off by each. 
Do alcohols make good fuels ? Which is the most often used 
for fuel ? Why ? Could they be used for illuminating 
purposes ? Why ? Write the equation to show the products 
formed when the alcohols burn. 

7. To a test tube half filled with water add a piece of 
camphor gum the size of a bean. Does it dissolve? Pour off 



74 COMMON ORGANIC COMPOUNDS 

the water and add 5 cc. of ethyl alcohol ; shake. Does it 
dissolve? This forms the so-called "spirits of camphor. " 
Add water to a crystal of iodine. Does it dissolve ? Pour 
off the water and add 5 cc. of alcohol. Result? This is 
called "tincture of iodine." What are its uses? Is alcohol 
a good solvent? Why are flavoring "extracts" largely 
alcohol ? Why is it used in patent medicines ? Should 
methyl alcohol be used for these purposes ? Why ? Ethyl 
alcohol is used to disinfect wounds. Should methyl alcohol 
be used for this purpose ? Why ? Ethyl alcohol is used 
for " alcohol rubs." Should methyl alcohol be used as 
well? Why? Why is methyl alcohol used for preserving 
fruits and vegetables in specimen jars rather than ethyl 
alcohol ? 

8. Summarize the properties of the common alcohols. 

9. Summarize the uses of each. 

10. What is the commercial source of each? 

B. Iodoform Test for Ethyl Alcohol (Grain Alcohol). 

1. Alcohol can often be detected by its odor or its taste. 
A better test is the following : To 10 cc. of liquid add 5 cc. 
of a solution of iodine in potassium iodide. Now add a solu- 
tion of sodium hydroxide one drop at a time, shaking the mix- 
ture well, till the iodine color vanishes. Warm gently, and 
let it stand for a few minutes. A yellow precipitate of iodo- 
form with its characteristic odor will be formed. If only a 
small amount of alcohol is present, the crystals may not form 
but the odor will be recognized. 

Try this test upon a solution of 2 cc. of alcohol in 10 cc. 
of water. 

Test a patent medicine for alcohol. 



SOME COMMON ALCOHOLS 75 

C. Ordinary Ether (C 2 H 5 ) : 0. 

Ether is formed by the action of concentrated sulfuric acid 
upon ethyl alcohol. It is called, for this reason, "sulfuric 
ether" or "ethyl ether." 

1. Obtain 5 cc. of ether. Note its odor. Place a drop 
on your hand. Is it volatile ? 

2. Dip the stirring rod into it and hold it in the flame ? 
Is ether inflammable ? 

3. Dissolve a drop of olive oil in the ether. Is it a good 
solvent? Why then is it not more often used for cleaning 
purposes ? 

4. What is the important use of ether ? 

D. Phenol or Carbolic Acid, C 6 H 5 OH. 

1. Pure phenol is a white crystalline substance. Examine 
a bottle of it, but do not remove any from the bottle. 

It is soluble in water. The solution is usually pink due 
to slight decomposition, and is called carbolic acid. 

2. Obtain 1 cc. of carbolic acid in a test tube. Describe 
its odor. Test it with red and with blue litmus. Is it a true 
alcohol ? Do not get any on the hands ; it causes serious 
burns. Alcohol is the antidote. What is carbolic acid used 
for? 

E. Glycerin, C 3 H 5 (OH) 3 . 

1. Obtain 5 cc. of glycerin in a test tube. Has it an odor? 
Taste it. Result? Pour about 1 cc. into another test tube 
half full of water. Shake. Is it soluble? 

2. Test the solution with litmus. Is it a true alcohol ? 

3. What is nitroglycerin? What is dynamite? What 
are they used for ? 

What important uses has glycerin in the home ? 



76 COMMON ORGANIC COMPOUNDS 

ORGANIC ACIDS 

An organic acid is composed of carbon, hydrogen, and 
oxygen. They all contain one or more carboxyl groups, 
COOH. They are nearly all crystalline solids. Some acids, 
such as acetic, tartaric, citric, and oxalic, have a sour taste 
and affect litmus as inorganic acids do. Others such as 
stearic, palmitic, benzoic, tannic, and salicylic acids are 
almost tasteless. As has been noted, these acids react with 
the alcohols (the organic bases) to form esters (organic salts) . 
These esters are the basis of many of our artificial flavoring 
extracts and perfumes. 

EXPERIMENT 34 
Properties and Uses of Some Common Organic Acids 

Materials. Acetic acid, alcohol, amyl alcohol, concentrated 
sulfuric acid, vinegar, tartaric acid, sodium bicarbonate, cream 
of tartar, citric acid, oxalic acid, potassium permanganate 
solution, tannic acid, ferrous sulfate. 

Apparatus. Test tubes. 

A. Acetic Acid, H(C 2 H 3 2 ) or CH 3 COOH. 

1. Note the odor of a dilute solution of acetic acid. 
Very carefully taste it. Test it with litmus paper. Result ? 

2. To 3 cc. of acetic acid add 3 cc. of ordinary alcohol, 
then, carefully, 3 cc. of concentrated sulfuric acid. Warm 
and note the sweet odor of ethyl acetate. This is a test for 
acetic acid. Write the equation and name each substance. 

C2H5OH+CH3COOH — ^ CH 3 COOC 2 H 5 +H 2 

Ethyl acetate is an organic salt formed from an organic 
acid and an alcohol. These salts are called esters. They 
have sweet odors and are often used for artificial flavorings. 



PROPERTIES OF SOME COMMON ORGANIC ACIDS 77 

To 3 cc. of acetic acid add 3 cc. of amyl alcohol and then 
3 cc. of concentrated sulfuric acid. Warm gently and note 
the odor of the ester amyl acetate. For what artificial flavor- 
ing is it used ? 

3. Obtain 3 cc. of vinegar. Smell it, taste it, and test it 
with litmus paper. What acid do you think is present? 
To prove your answer add alcohol and sulfuric acid as in 
(2) and obtain the ester test. What acid is in vinegar? 
For what purposes is vinegar used in cooking? 



B. Tartaric Acid, Ho(C 4 H 4 6 ) or C 2 H 4 2 (COOH) 



1. Obtain a crystal of tartaric acid. Describe its taste. 
Pulverize the crystal and dissolve a small portion in water. 
Test the solution with litmus. Has tartaric acid the charac- 
teristic property of an acid ? 

Mix the rest of the powdered crystal with an equal amount 
of dry sodium bicarbonate. Is there any action? Now 
add water. What is given off? Write the equation and 
name each substance. 

NaHC0 3 +H 2 C 4 H 4 6 H — ^ HNaC 4 H 4 6 +H 2 0+C0 2 

Tartaric acid is used in baking powders. Why ? (See 
Experiment 29 on Carbonates.) 

2. Cream of tartar is a salt of tartaric acid HKC 4 H 4 6 
(hydrogen potassium tartrate). Taste it. Dissolve a small 
amount in water and test with litmus. Result ? Mix a small 
amount with sodium bicarbonate. Is there any action? 
Now add water. Result? Write the equation and name 
each substance. 

HKC 4 H 4 6 +NaHC0 3 — ^ NaKC 4 H 4 6 +H 2 0+CQ2 



78 COMMON ORGANIC COMPOUNDS 

3. What is the source of cream of tartar and tartaric acid? 

4. What are the little hard " lumps" often found in canned 
grapes that have been kept for some time ? 

C. Citric Acid, H s (C^ b 7 ) or C 3 H 5 0(COOH) 3 . 

1. Obtain a crystal of citric acid. Describe its taste. 
Dissolve it in water and describe its action on litmus. In 
what fruits is this acid chiefly found ? What is its commercial 
source ? 

2. How may it be used in making artificial lemonade? 

D. Oxalic Acid, H 2 C 2 4 or (COOH) 2 . 

1. Obtain a few crystals of oxalic acid. 

Caution : Do not taste them. 

Oxalic acid is a poison. In what plants is oxalic acid 
found ? 

2. Describe the appearance of the crystals. 

3. Place the crystals in half a test tube of cold water. 
Shake the tube. Result? 

4. Now heat the water in the tube. Is oxalic acid more 
soluble in hot or cold water? Test the solution with litmus 
paper. Result ? 

5. Make a stain upon your hand with a solution of potas- 
sium permanganate and remove it by applying some of the 
solution of oxalic acid that you have just prepared. Wash 
the hand thoroughly. A solution of oxalic acid is often used 
in preparations for removing stains from the hands and nails. 

6. Place a teaspoonful of bleaching powder in 25 cc. of 
water. Stir well at two-minute intervals for ten minutes, then 
filter. Call the filtrate, Solution No I. Dissolve 5 grams 
of oxalic acid in 50 cc. of water. Call this Solution No. II. 
This is the common ink eradicator. Try it. 



PROPERTIES OF SOME COMMON ORGANIC ACIDS 79 

E. Tannic Acid (sometimes called Tannin). 

1. Obtain 1 gram of tannic acid. Describe its appearance. 
What is its commercial source ? 

2. Put it into half a test tube of cold water. Does it dis- 
solve ? Heat the tube. Does it dissolve in hot water ? Test 
the solution with litmus. Result? Cautiously taste the 
solution. Describe the taste. 

3. To half of the tannic acid solution add a few drops 
of ferric chloride, FeCl 3 . Result ? This is an ink. 

4. To the other half of the solution add a few drops of 
ferrous sulfate, FeS0 4 . Notice that the black precipitate 
(the ink) is not formed at once, but forms slowly as the 
ferrous salt is oxidized by the air to the ferric salt. Tannic 
acid and ferrous sulfate are used in the manufacture of inks. 
These inks write blue at first because a blue dye is added. 
The ink turns black on standing because the ferrous salt is 
oxidized to the ferric salt by the oxygen of the air, and ferric 
tannate is a deep blue-black. 

5. Many plants contain tannic acid. It is in oak bark, 
sumach leaves, and the leaves of other trees, in tea leaves, in 
coffee berries, in rose leaves, and rose petals. 

In making rose beads the crushed wet rose petals are al- 
lowed to stand in a rusty iron pan, or powdered "copperas" 
(ferrous sulfate) is added. The mass becomes very black. 
Explain. 

6. Tannic acid makes skins tough and "leathery." It is, 
therefore, used in " tanning " hides in the manufacture of 
shoes and gloves. 

What is one objection to the constant drinking of beverages 
containing much tannic acid like strong green tea or strong 
coffee ? 



80 COMMON ORGANIC COMPOUNDS 

F. A Note on Esters. 

In A, 2 of this experiment the esters, ethyl acetate and 
amyl acetate, were prepared. Ethyl acetate is called artificial 
oil of apple. Amyl acetate is artificial banana oil. Artificial 
oil of wintergreen is methyl salicylate, the ester (organic 
salt) prepared from methyl alcohol (organic base) and sali- 
cylic acid (organic acid). Nearly all the oil of winter- 
green on the market is the artificial product. 

Most esters are more or less fragrant volatile oils. They 
are usually insoluble in water but soluble in alcohol, and this 
alcoholic solution is called an "extract." These extracts 
form the basis of many of our flavoring extracts and perfumes. 

Fats are solid esters also insoluble in water but without 
odor. 

If the alcohol glycerin, C3H 5 (OII) 3 , combines with 
stearic acid, Ci 7 H 35 COOH, an ester glyceral stearate, 
(Ci7H3 5 COO)3C3H 5 , is formed. This is a fat called stearin. 
An ordinary fat such as beef tallow is made up largely of this 
fat and glyceral palmitate, (CisHaiCOO^CsHs, and glyceral 
oleate, (C 17 fhzCOO)zCJI 6 . 

EXPERIMENT 35 

(Class Experiment) 

Fuels and Illuminants 

Materials. Sawdust, coal, ice. 

Apparatus. Test tubes, large glass test tube, side-necked test 
tube, delivery tube, clay pipe stem. 

A. Solid Fuels. 

1. Wood: What woods are the most commonly used for 
heating purposes in this region? Which is best? Why? 



FUELS AND ILLUMINANTS 81 

What are the chief elements in wood? What are the prod- 
ucts formed when wood is burned in the air ? 

If wood is heated without air entirely different products 
are formed. Half fill a hard-glass test tube with small pieces 
of hard wood or sawdust. Clamp the test tube in a hori- 
zontal position on the ring stand. By means of a right-angled 
delivery tube attach the hard-glass test tube to a side-necked 
test tube by means of two well-fitted one-holed stoppers. 
Attach a jet to the side-necked test tube. Keep the side- 
necked test tube cool by standing it in a beaker of ice water. 
Heat the wood till no further change takes place. Test the 
gas that escapes from the side-necked test tube. Will it 
burn ? 

When the hard-glass tube is cold examine the contents. 
Remove the black residue. What is it? 

Note the odor of the liquid in the side-necked test tube. 
Test with litmus. Result? Is water formed when wood is 
decomposed? Is an acid formed? What acid chiefly? 
What compounds are made commercially by heating hard 
wood in the absence of air ? 

When a substance is heated in the absence of air, the process 
is called destructice distillation. 

2. Coal: What is the source of coal ? Of what is it chiefly 
composed? What are the products formed when it is com- 
pletely burned in air? 

Half fill a hard-glass test tube with small pieces of soft coal. 
Clamp the test tube in a horizontal position on the ring 
stand. Set up the apparatus as in A. Heat the coal till 
no further change takes place. What is the gas that is 
formed? What remains in the hard-glass tube? What is 
the gas that is formed ? What collects in the side-necked test 



82 CHEMISTRY OF FOODS 

tube? Test for an acid. Result? Test for a sulfide. What 
commercial products may be obtained by the destructive 
distillation of coal ? 

B. Liquid Fuels and Illuminants. 

1. Alcohol: Why is grain or ethyl alcohol not more com- 
monly used for fuel ? What is the color of the alcohol flame ? 
Could it be used for illuminating purposes ? 

2. Crude Petroleum: This fuel is used in many furnaces 
where intense even heat is needed. Visit the furnace room 
at your school or the large range in the lunch house and note 
the intense heat produced by the burning jet of crude oil. 
Describe the burner. 

3. Gasoline: What is the source of gasoline? Can it be 
used for fuel ? How ? Can it be used for lighting purposes ? 
How? 

4. Kerosene: What is the source of kerosene? How can 
it be made to burn with a blue flame ? 

C. Gaseous Fuels and Illuminants. 

Some of the gases used for fuels and illuminants are natural 
gas, coal gas, and acetylene. What is natural gas ? 

Explain how the same gas can be used either for lighting 
purposes or for fuel. What is a Welsbach mantle ? Explain 
its use. 

X. CHEMISTRY OF FOODS 

In studying the chemistry of foods, the Food Chemistry 
outline in the Appendix of this manual will be found useful. 
The following are good reference books : 

Bulletin No. 28, U. S. Department of Agriculture, Appendix A. 
Bulletin No. 13, American School of Home Economics. 



WATER IN FOODS 83 

Weed, Chemistry in the Home. 

Wellman, Food Study. 

Sherman, Food Products. 

Snell, Elementary Household Chemistry. 

Leach, Food Inspection and Analysis. 

Brownlee, Fuller, and others, Chemistry of Common Things. 



INORGANIC CONSTITUENTS OF FOODS 

EXPERIMENT 36 

Water in Foods 

Materials. White bread, milk, meat, potato. 

Apparatus. Laboratory balances, drying oven, evaporating dish. 

A. The Presence of Water in Foods. 

How is the presence of water in food determined ? (See 
Experiment 12 C.) Test four foods for water. 

B. The Amount of Water in Foods. 

1. To determine exactly how much water a substance 
contains it is weighed, then dried and weighed again. The 
loss in weight is the weight of the water that was in the 
substance. Divide the weight of the water by the weight 
of the substance before drying and multiply the result by 
100 to give the per cent of water in the substance. 

Find the per cent of water in bread as follows : Label your 
evaporating dish with your name and weigh it. Obtain the 
largest cube of bread that will go into the dish and weigh both 
as carefully as you can on the laboratory balance. Place the 
dish and the bread in the drying oven for about six hours, 
keeping the temperature below 106° C. Why? When 
completely dry cool and weigh. Tabulate the results as 
follows : 



84 CHEMISTRY OF FOODS 

(a) Weight of empty dish = g. 

(b) Weight of dish and bread before drying = g. 

(c) Weight of dish and bread after drying = g. 

(d) Weight of bread (b)-(a) = g. 

(e) Weight of water in bread (5) — (c) = g. 

(/) Per cent of water in bread (e) h- (d) X 100 = % 

2. From the table in the Appendix make a list of five 
foods which contain much water (80 %-100 %), five which 
contain a medium amount of water (15 %-S0 %), and five 
containing very little water (less than 15 %). 

3. What tissues of the body contain much water? What 
tissues contain the least water? 

4. Of what use is water to the body ? 



INORGANIC SALTS IN FOODS AND BONES 

EXPERIMENT 37 

Inorganic Salts in Foods (Mineral Matter or Ash) 

Materials. Bones that have soaked for at least two days in 
hydrochloric acid, ammonium hydroxide, milk, meat, potato, 
bread. 

Apparatus. Porcelain crucibles, clay triangle, evaporating dish. 

A. Inorganic Salts in Foods. 

Inorganic salts do not burn; they remain as ash, when 
the organic matter of the food has been burned away. 

1. To show the presence of inorganic salts in a food place 
about 1 gram of the food in a porcelain crucible and heat 
with the crucible inclined. In this way, heat milk, meat, 
potato, and bread. 

(Four students may work together, the first heating milk, 



INORGANIC SALTS IN FOODS (MINERAL MATTER OR ASH) 85 

the second meat, etc. Each student should make observa- 
tions and reports on four foods.) 

2. From the table in the Appendix make a list of foods 
containing much mineral matter and a list of foods contain- 
ing little or no mineral matter. 

B. To Show the Presence of Inorganic Salts in Bones. 

1. Clean a small bone by boiling in water. Place the 
clean bone in a beaker of hydrochloric acid and allow it to 
stand for two days. Explain the change that has taken 
place in the bone. Keep the bone. 

2. Place 10 cc. of the clear liquid in an evaporating dish 
and evaporate to dryness. What is the dry residue that 
remains ? 

3. Prove the presence of calcium salts in the ash by dis- 
solving it in 5 cc. of hydrochloric acid. Filter. Make the 
solution alkaline with ammonium hydroxide. What is the 
white precipitate chiefly? 

4. What tissues of the body contain much mineral matter 
and what tissues very little ? 



CARBOHYDRATES 

Carbohydrates are organic compounds which form the 
most important part of our foods. They contain no nitro- 
gen (non-nitrogenous). They are composed of carbon, 
hydrogen, and oxygen, the hydrogen and oxygen usually 
being present in the proportion in which it is found in water, 
that is, twice as many atoms of hydrogen as oxygen. The 
starches and the sugars are the most important carbohydrates 
found in foods. 



86 CHEMISTRY OF FOODS 

The Starch Group (C 6 Hi O5)» 
EXPERIMENT 38 
Starch and Dextrin 

Materials. Corn starch, rice starch, wheat starch, potato starch, 
dextrin, concentrated sulfuric acid, Fehling's solution, dilute 
sulfuric acid, sodium carbonate, litmus paper, iodine solution, 
potato, meat, milk, apple, banana, nuts, rolled oats, raisins. 

Apparatus. Test tubes, microscope, labels, asbestos mat. 

A. Properties of Starch. 

1. Obtain about one gram of corn starch, rice starch, 
wheat starch, and potato starch in separate tubes. Is there 
any difference in the appearance of each ? 

2. Mount a few grains of each on microscope slides and 
draw the appearance of each under the high power. 

3. Add 10 cc. of water to each tube. Shake the mixture 
well and then let it stand for one minute. Does starch 
dissolve in cold water ? 

4. Shake the mixture of corn starch and water again and 
then boil it for a few minutes. (Keep this for 9.) 

5. Gently heat a little corn starch in a dry test tube until 
it becomes brown. What is formed ? Taste it. Try the 
solubility of some pure dextrin in water. What is dextrin 
used for? Why is the brown crust of bread sweet? 

6. Heat strongly one gram of starch in a dry test tube. 
What collects on the sides of the tube ? Explain. What re- 
mains in the tube ? What does this show about the composi- 
tion of starch ? Write an equation to show what took place. 

7. Add a few drops of concentrated sulfuric acid to some 
dry starch in a test tube. Warm gently. Explain results. 
How does this also show the composition of starch? 



STARCH AND DEXTRIN 87 

8. Burn a small lump of starch on your asbestos mat. 
What products are found ? Write an equation to illustrate. 

9. To 5 cc. of starch paste prepared in (4) add 5 cc. of 
Fehling's solution and boil. Result? (To prepare Feh- 
ling's solution, see Appendix.) 

10. To 10 cc. of starch paste add 10 cc. of dilute sulfuric 
acid. Boil for five minutes. Add solid sodium carbonate 
till the mixture is alkaline to litmus, then add Fehling's solu- 
tion and boil. Result? 

Note : If a red precipitate is not obtained, try again. The starch combines 
with a molecule of water to form glucose (grape sugar). Glucose is a reducing 
sugar and reduces the copper sulfate in the Fehling's solution to cuprous oxide. 
Cuprous oxide is the red precipitate. When a substance like starch takes 
up water and becomes a new substance, it is said to hydrolyze. The process is 
called hydrolysis. There are several ways of hydrolyzing substances : (i) By 
boiling with a dilute acid, (2) boiling with a base, (3) by means of an enzyme or 
ferment. 

How is starch caused to hydrolyze? Could any acid be 
used other than sulfuric acid? Write this equation for the 
hydrolysis of starch and name each substance : 

C 6 H 10 O 5 +H 2 O (by means of H 2 S0 4 ) — >■ C 6 H 12 6 . 

B. The Iodine Test for Starch. 

1. Obtain about 10 cc. of a solution of iodine in one of 
your clean test tubes. To some dry starch add about 1 cc, 
of iodine solution. Results? 

2. To a test tube half full of water add two drops of cold 
starch paste. Shake well, then add about two drops of the 
iodine solution. Results? Boil till the color disappears, 
then cool again and the color will return if you have not 
boiled it too long. This is called the iodine test for starch. 

3. To detect the presence of starch in foods the food should 
(1) be broken into small pieces or powdered. Why? (2) 



88 



CHEMISTRY OF FOODS 



It should be boiled two or three minutes in water. Why? 
(3) It should be cooled. Why? (4) Two drops of iodine 
solution should be added. 

4. Test the following foods for starch according to the 
method above and record the results in a table : potato, 
meat, milk, apple, banana, nuts, rolled oats, raisins. 

Of what use to the body is starch? 



Much Starch 


Little Starch 


No Starch 









CELLULOSE 

Cellulose forms the walls of the cells of plants. It is 
most abundant in the roots and stems, less in the leaves, and 
least in the fruit. "Seed hairs" are almost pure cellulose. 
Since cotton fibers are seed hairs, cotton is almost pure cellu- 
lose. The fiber in young tree trunks is used for paper. 
Cellulose is not digestible, but it forms an important part of 
food, for it gives it the needed bulk. 



EXPERIMENT 39 

Cellulose 

Materials. Carrots, beets, celery, potato, cabbage, lettuce, ap- 
ples, grapes, dilute hydrochloric acid, dilute sodium hydroxide, 
solid sodium carbonate, zinc chloride, Schweitzer's reagent (see 
Appendix), concentrated nitric acid, alcohol, ether. 

Apparatus. Test tubes, beaker. 



CELLULOSE 89 

A. Occurrence of Cellulose, (C 6 Hi Oo)«. 

1. Examine carefully roots (carrot, beet), stems (celery, 
potato), leaves (cabbage, lettuce), and fruits (apples, grapes). 

Draw the position of the chief cellulose fibers in each. 

2. Name five vegetables or fruits with much cellulose 
and five with little or no cellulose. 

B. Properties of Cellulose. 

1. Test the solubility of cellulose (a small amount of cot- 
ton in each case) in water, dilute hydrochloric acid, dilute 
sulfuric acid, and dilute sodium hydroxide. What is the 
result in each case? Is the cellulose digestible? Of what 
value is it in the foods? 

2. Test cellulose (cotton) with a solution of iodine. Re- 
sult? 

3. Test cellulose (cotton) with Fehling's solution. Re- 
sult after boiling ? 

4. Cover a little cotton in a test tube with concentrated 
sulfuric acid. Allow it to stand two minutes. Neutralize 
the acid with sodium carbonate (till effervescence ceases and 
it turns red litmus blue). Now add Fehling's solution and 
boil. Explain and write equations. What possible use 
does this suggest for old papers and rags ? 

5. (Instructor) : Test the solubility of cellulose in a solu- 
tion of zinc chloride in concentrated hydrochloric acid. 

6. (Instructor) : Prepare a fresh solution of cuprous 
ammonia or Schweitzer's reagent according to the method 
given in the Appendix. Show the solubility of cellulose in 
this solution. Reprecipitate the cellulose by adding hydro- 
chloric acid. This is a test for cellulose. 

7. (Instructor): Prepare " nitro-cellulose " or "guncot- 



90 CHEMISTRY OF FOODS 

ton" and "collodion" by mixing 20 cc. of concentrated 
sulfuric acid and 10 cc. of concentrated nitric acid. Cool 
this to room temperature. Immerse absorbent cotton or 
clean cotton gauze in this mixture for about one minute. 
Wash well with cold water, wring it out, and hang it up to 
dry. This is "gun cotton." 

Burn a piece of guncotton and compare with the burning 
of untreated cotton. 

Shake a portion of the dry guncotton in a mixture of 
equal parts of alcohol and ether. The clear solution is 
"collodion." Place a little in a glass plate and allow it to 
stand. Result? What is collodion used for? What is 
" New Skin " ? What is celluloid ? 

8. Is cellulose digested? Is it of use in foods? Explain. 

GUMS AND PECTIN 

Gums are compounds closely related to the carbohydrates, 
having very complex constitutions. They are generally solu- 
ble in water but not in alcohol. The water solutions when 
cold form jellies, or sticky mucilage-like solutions. 

Pectin is a carbohydrate found in fruits, which causes the 
juices to " jelly " when boiled with sugar. Pectin will produce 
a jelly only in the presence of at least half of one per cent of 
acid. Sugar also helps to precipitate the pectin and to form 
the jelly. 

EXPERIMENT 40 

Gums and Pectin 

Materials. Gum arabic or gum tragacanth, agar-agar or Iceland 

moss, iodine solution, Fehling's solution, concentrated sulfuric 

acid, solid sodium carbonate, alcohol, cranberries. 
Apparatus. Test tubes, beaker. 



GUMS AND PECTIN 91 

A. Gums. 

1. Note carefully the physical properties of gum arabic 
and agar-agar with special reference to color, odor, taste, and 
form. 

2. Dissolve about one gram of gum arabic in a half test 
tube of boiling water. Boil one minute. Cool the solution. 
What is formed ? Repeat, using agar-agar. What is formed ? 

3. To about 1 cc. of the cool gum arabic solution add a 
few drops of iodine solution. Result? Repeat, using agar- 
agar. Result ? 

4. To about 1 cc. of the gum arabic solution add Fehling's 
solution and boil. Result? Repeat, using agar-agar. Re- 
sult? 

5. To the remainder of the gum arabic solution add (cau- 
tiously) 5 cc. of concentrated sulfuric acid and boil two 
minutes. Add solid sodium carbonate till the acid is neu- 
tralized, then add Fehling's solution and boil. Explain. 

6. Try to dissolve one gram of gum arabic in alcohol. 
Result? Repeat, using agar-agar. Are gums soluble in 
alcohol ? 

7. How are some of the gums used in the preparation of 
foods? 

8. Give some of the commercial uses of gums. Why is 
it used by bacteriologists for culture media ? 

B. Pectin. 

1. Slice five cranberries in your beaker, add 50 cc. of 
water, and boil ten or twenty minutes. Filter while hot. 

2. To 15 cc. of the clear filtrate add 15 cc. of alcohol. 
Result? (A jelly-like precipitate of pectin should be formed. 
This is a test for pectin in fruits.) 



92 CHEMISTRY OF FOODS 

3. To 15 cc. of the clear filtrate add 10 grams of sugar and 
boil for ten minutes. Cool. A jelly indicates the presence 
of pectin. 

Do cranberries contain pectin? 

4. To the remainder of the filtrate add 5 cc. of concen- 
trated sulfuric acid. Boil for five minutes. Neutralize 
the acid with solid sodium carbonate. Then add Fehling's 
solution and boil. Result? (Like starch, pectin is hydro- 
lyzed to reducing sugars by long boiling with a dilute acid, 
or by boiling for a short time with a strong acid.) 

5. Summarize the necessary precautions to be observed 
in making jelly. 

6. What fruits contain much pectin? Which contain 
very little ? 

7. Repeat B, 1 and B, 2, using an apple and one other 
fruit. Report the presence or absence of pectin. 

Test also a beet for pectin. Could jelly be made from a 
beet? 

SUGARS 

The sugars are carbohydrates widely distributed in nature. 
They form crystals and dissolve in water. They have a 
sweet taste. There are two groups of sugars : (1) The 
monosaccharides or monoses, including glucose, fructose, and 
gelactose having the general formula C6Hi 2 6 , and (2) the 
disaccharides or dioses, including sucrose, lactose, and maltose 
having the general formula C12H22O11. 

Glucose called grape sugar or dextrose is found in grapes. 
Fructose called fruit sugar or levulose is formed with glucose 
when sucrose is hydrolyzed. Gelactose is formed with 
glucose when lactose is hydrolyzed. 



SUGARS 93 

EXPERIMENT 41 
Sugars 

Materials. Sucrose (cane sugar), lactose (milk sugar), dextrose 
(grape sugar), in five-gram portions, concentrated sulfuric acid, 
iodine solution, Fehling's solution, dilute sulfuric acid, solid so- 
dium carbonate, raisins, honey, rice, beets, lemons, flour. 

Apparatus. Test tubes, small beaker. 

A. Physical Properties of Sugars. 

1. Obtain 5 grams of sucrose or cane sugar, C12H22O11. 
Note its form and taste. Place about 1 gram in a test 
tube half full of cold water. Result? 

2. Obtain 5 grams of lactose, milk sugar, C12H22O11, and 
note its form and taste. Place about 1 gram in a test tube 
half full of cold water. Heat the water. Is it more soluble 
in hot or in cold water ? Is it as sweet as cane sugar ? Is 
it as soluble as cane sugar? 

3. Repeat (2), using grape sugar, C6H12O6, sometimes called 
glucose or dextrose. Is it as sweet as cane sugar? Is it 
as soluble? Will it crystallize as easily? 

B. Chemical Properties of Sugars. 

1 . Place about one gram of sucrose in a dry test tube and 
heat until it melts. This is called barley sugar and when 
cool it forms a pale yellow glassy mass. 

Heat more strongly. Note the change in color, odor, and 
taste. What is the brown sirup formed? 

Now heat the tube intensely until the substance decom- 
poses. What collects on the cool sides of the test tube? 
What remains in the tube? What does this prove con- 
cerning the composition of cane sugar (sucrose) ? Is it true 



94 CHEMISTRY OF FOODS 

carbohydrate? What is its formula? Write the equation 
to show its complete decomposition. 

2. In like manner heat 1 gram of lactose until it is com- 
pletely decomposed. Result? Is it also a true carbo- 
hydrate? What is its formula? Write the equation to 
show its complete decomposition. 

3. Repeat (2), using grape sugar. Is it a true carbohy- 
drate? What is its formula? Write the equation to show 
its complete decomposition. 

4. Place 1 gram of each sugar in three different test tubes 
and cover with concentrated sulfuric acid. Warm if neces- 
sary. Note the results in each case and explain fully. Write 
an equation in each cas^ to show the decomposition of the 
sugars by acid. This is a second method to prove sugars 
to be carbohydrates. 

5. Dissolve one gram of each sugar in hot water in separate 
test tubes, cool, and add a few drops of iodine solution to each. 
Do sugars affect iodine solution ? 

6. Dissolve 1 gram of grape sugar in hot water, add 5 cc. of 
Fehling's solution, and boil. A red or yellow precipitate of 
cuprous oxide, CU2O, is formed. Grape sugar reduces the 
copper sulfate in the Fehling's solution to cuprous oxide 
which forms the red precipitate. Such a sugar is called a 
reducing sugar. 

7. Dissolve 1 gram of sucrose, cane sugar, in water, add 
Fehling's solution, and boil. Is sucrose a reducing sugar? 

8. Repeat (7), using lactose. Is lactose a reducing 
sugar ? 

9. Place 5 grams of sucrose in your small beaker. Dissolve 
in 25 cc. of water. Add 10 cc. of dilute sulfuric acid and 
boil 1 minute. Now add solid sodium carbonate until the 



SUGARS 95 

solution is alkaline to litmus, then add Fehling's solution and 
boil. Is a reducing sugar present? 

The sugar is hydrolyzed as was starch in Experiment 38. 
In this case two reducing sugars are formed, dextrose and 
levulose. Both have the formula C 6 Hi 2 6 . Write the 
equation for the hydrolysis of sucrose, naming each substance. 

C 12 H 22 O n +H 2 (by means of H 2 S0 4 ) ^ C6H 12 6 +C 6 H 12 6 

Now explain why lemon juice or vinegar is used in making 
taffy or in general to prevent the graining of cane sugar 
sirup. 

10. Glucose is a fermentable sugar, alcohol and carbon 
dioxide being formed. 

C 6 H 12 6 +yeast — ^2 C 2 H 5 OH+2 C0 2 

Lactose and cane sugar are not fermentable by pure yeast. 
An enzyme contained in the yeast hydrolyzes these sugars, 
forming some glucose. Then the glucose formed ferments. 

11. Summarize the results of the tests on the three sugars 
in a table under the following heads : Taste as compared 
with cane sugar. Solubility in water. Action of intense 
heat. Result of boiling with dilute acids. Action of 
Fehling's solution. Action of pure yeast. 

C. Method of Testing Foods for Reducing Sugars. 

1. Boil the substance in water after breaking it into small 
pieces, add Fehling's solution and boil again. A red precipitate 
of cuprous oxide indicates the presence of a reducing sugar. 

2. Test the following foods for a reducing sugar. Name 
the sugar present if possible, (a) Raisins, (b) Honey, (c) 
Rice, (d) Meat, (e) Beet, (/) Lemon, (g) Flour. 

3. Of what use are the sugars to the body? 



96 CHEMISTRY OF FOODS 



FATS AND OILS 



A fat is an ester. An ester is the organic salt formed 
when an alcohol (organic base) combines with an organic 
acid. When the alcohol glycerin, C 3 H 5 (OH) 3 , combines 
with stearic acid, Ci 7 H 35 COOH, the fat glyceryl stearate 
(stearin), (CnHasCOO^CsHs, is formed. 

If glycerin combines with palmitic acid, C15H31COOH, the 
fat glyceryl palmitate, (C^HsiCOO^CsH^ (palmitin), is 
formed. 

If glycerin combines with oleic acid, C17H33COOH, the fat 
glyceryl oleate, (Ci7H33COO) 3 C3H 5 (olein), is formed. 

Ordinary fats are mixtures of these three fats. In solid 
fats, stearin and palmitin predominate. In oils olein pre- 
dominates. 

Fats are non-nitrogenous, organic compounds. They 
are composed of carbon, hydrogen, and oxygen, but they 
are by no means carbohydrates. 

EXPERIMENT 42 
Fats and Oils 

Materials. Lard, olive oil, butter, cottonseed oil, gasoline, ether, 
chloroform, carbon tetrachloride, solution of egg albumen in 
water, iodine solution, Fehling's solution, sodium hydroxide 4 N, 
Sudan III, castor beans, boiled egg yolk, walnuts, chocolate, 
grated cheese. 

Apparatus. Test tubes, evaporating dish, beakers. 

Note : Do not throw fats or oils into the sink, put them in the jars 

A. Physical Properties of Fats and Oils. 

1. Obtain about 5 grams of each of the following : lard, 

olive oil, cottonseed oil. What is the source of each? 



FATS AND OILS 97 

2. Note the color, odor, and taste of each. Are they 
soluble in water? To the tubes add respectively 50 cc. of 
gasoline, ether, chloroform, and carbon tetrachloride. 

Caution: Have no flames near. 

Shake well and then look for the oil. Result? Now ex- 
plain how a grease spot on clothing may be removed by one 
of these solvents. Which is the best to use? Why? In 
removing a grease spot why apply solvent at the outside 
and work toward the center of the spot ? 

3. Place 1 cc. of olive oil in a test tube. Add 5 cc. of a 
solution of egg albumen in water. Shake vigorously for a 
minute. Result? This is called an emulsion. Let it 
stand and note that in time the oil will come to the top. 
The more perfect the emulsion the longer it will take for the 
oil to separate out. Milk is an example of a natural emul- 
sion. Mayonnaise dressing is an example of a prepared emul- 
sion. The disagreeable taste of castor oil is masked by 
preparing an emulsion by first adding orange juice, then 
baking soda, and stirring rapidly. 

B. Chemical Properties of Fats and Oils. 

1. In a test tube place a lump of lard about the size of 
a bean. Add 5 cc. of a solution of iodine. Result? 

2. In another test tube place the same amount of lard 
and add 5 cc. of Fehling's solution and boil. Result? 

3. In a clean evaporating dish place 2 grams of lard ; warm 
gently. Result? Heat the lard more and more strongly 
and note results. The strong, irritating odor from hot lard 
or other fats or oils is due to the formation of acrolein. 

4. To three drops of cottonseed oil add J test tube of 
sodium hydroxide and boil for a minute or until the oil can 



98 CHEMISTRY OF FOODS 

no longer be seen. A soap is formed. The process is called 
saponification. Write two equations to show the reactions 
that took place. Name all substances. 

C. Tests for Fats and Oils. 

1. The reagent Sudan III stains fats and oils. Cut open a 
castor bean or a sunflower seed ; apply a drop of the reagent. 
Result? In like manner test boiled egg yolk for fat. 

2. Some substances contain sufficient fat to give the 
"grease spot" test. Rub a piece of walnut on a page of 
your scratch pad placed on the table. Is a grease spot 
formed? Warm the spot over the burner. It should not 
disappear. In this way test chocolate. 

3. The fat may be extracted from the substance by mixing 
well with ether or gasoline. The gasoline will dissolve the 
fat and then if allowed to evaporate, the fat will be left. 

Put about 10 grams of grated cheese in one of your 
beakers. Add 25 cc. of gasoline ; stir well. 

Caution: Have no flames near. 

Filter into your beaker and allow the filtrate to evapo- 
rate. What remains in the beaker? 

4. What is the use of fats to the body ? From the Appen- 
dix make a list of 10 foods containing much fat (80 % to 100 %). 
Make a list of 10 foods containing very little or no fat (10% 
to none) . Name five fats or oils of commercial value and give 
their uses. 

NITROGENOUS SUBSTANCES 

Nitrogenous substances are very complex compounds, 
found in some plant and nearly all animal tissues. The 
most important nitrogenous substances are called proteins. 
They are composed of carbon, hydrogen, oxygen, and about 



THE ALBUMENS AND CASEIN 99 

14 % of nitrogen with varying amounts of sulfur and phos- 
phorus. The proteins may be classified into four groups : 
(1) Those soluble in cold water and coagulated by hot water, 
called the albumens (egg albumen, blood albumen, milk 
albumen). (2) Those soluble in hot or cold water (casein 
in milk). (3) Those not soluble in hot or cold water, called 
globulins (myosin in meat, gluten in flour, and legumen in 
peas and beans) . (4) Those soluble in hot water but not in cold, 
called albuminoids or gelatinoids because when the hot solu- 
tion is allowed to cool a jelly is formed (collagen from skin, 
cartilage, and bones, and keratin from hair, horns, and hoofs). 

EXPERIMENT 43 
The Albumens and Casein 

Materials. Fresh egg albumen, concentrated nitric acid, am- 
monia, Millon's reagent, dry blood albumen, dry egg albumen, 
soda lime, red litmus paper, fresh milk, rennin, dilute hydro- 
chloric acid or acetic acid. 

Apparatus. Test tubes, funnel, filter paper, evaporating dish, 
stirring rod. 

A. The Albumens (Soluble in Cold Water, Coagulated by Hot Water). 

1. Obtain 1 cc. of fresh egg albumen in a test tube. Note 
its physical properties. Add 20 cc. of cold water and shake 
well. Does it dissolve? 

2. Heat the solution of egg albumen. Result? 

3. Filter the coagulated albumen and place a portion of 
it in your evaporating dish. Heat slowly and note the pecul- 
iar odor of burning protein. Explain. This is the " burn- 
ing test" for proteins. 

4. To another portion of the coagulated albumen add 



100 CHEMISTRY OF FOODS 



E 



concentrated nitric acid till the albumen is covered. Warm 
gently. Result? Now pour off the acid, rinse with water, 
and add ammonia. Result? This is the xanthoproteic 
test for proteins. 

5. Obtain about 10 cc. of blood albumen in water. Add 
1 cc. of Millon's reagent and boil. Result? This is Millon's 
test for proteins. 

6. Obtain 2 grams of dry blood or egg albumen, mix with 
soda lime, and heat in a test tube. Note the odor and hold 
a piece of moist red litmus at the mouth of the tube. What 
is the gas given off? Explain. This is the decomposition 
test for proteins. 

7. Obtain 20 cc. of fresh milk in your evaporating dish 
and heat. What are the scums formed ? By means of the 
stirring rod place some of the scum in a test tube and apply 
the xanthoproteic test (see 4 above). Result? 

B. Casein (Soluble in Hot and Cold Water). 

1 . Is casein soluble in hot water ? How do you know ? 

2. To a portion of the milk used in A, 7 add dilute hydro- 
chloric acid or acetic acid. Result ? 

To another portion add rennin and warm gently. Allow 
it to cool for five minutes. Result? 

3. To a part of the casein apply the burning test. Result ? 

4. Apply the xanthoproteic test. Result ? 

5. Apply the Millon's test. Result? 

6. Apply the decomposition test, using soda lime. Result ? 

Questions 

1 . If albumen and casein were in a solution together, how 
could you separate one from the other ? 

2. What are some of the tests for albumen and casein ? 



THE GLOBULINS AND ALBUMINOIDS 101 

EXPERIMENT 44 

The Globulins and Albuminoids 

Note to instructor: Have part i of A done at home. The gluten loaves 
should be submitted for approval and credit. 

Materials. Flour, nitric acid, ammonia, Millon's reagent, 
soaked beans, bones soaked in hydrochloric acid for a week, 
soup bones, hair or feathers, sodium hydroxide 4 N, sodium 
plumbite solution. 

Note: Sodium plumbite solution may be prepared by adding sodium 
hydroxide to lead acetate solution until the precipitate first formed dissolves 
on heating. 

Apparatus. Muslin bag, test tubes, evaporating dish. 

A. The Globulins (Insoluble in Hot or Cold Water). 

Gluten is the globulin found in wheat and other cereals. 

1. Into a cup full of flour stir just enough water to make a 
heavy dough. Place the dough in a muslin bag and knead 
it in the hand in a running stream of water till the water 
runs through clear. What part of the flour is removed in 
this manner? Examine the gluten remaining in the bag. 
What are its physical properties? Is it soluble in cold 
water? Leave about one fourth of the gluten in the wet 
muslin bag and take it to the laboratory for the chemical 
tests. Bake the other three fourths in a moderate oven. 
Result ? Take the gluten loaf to the instructor for credit. 

2. Place a piece of unbaked gluten about the size of a 
bean in a test tube ; add water and boil. Is gluten soluble 
in hot water ? 

3. Place a similar piece in your evaporating dish. Heat 
and note the odor. 

4. Apply the xanthoproteic test. Result ? 



102 DIGESTION OF FOOD 

5. Apply the Millon's test. Result? Is gluten a true 
protein ? 

6. Myosin is the globulin found in meat. Burn a small 
piece of meat and note the odor. Apply the xanthoproteic 
test. Result? 

7. Legumen is the globulin in peas and beans. Burn 
half a bean that has soaked overnight. Result? Apply 
the xanthoproteic test to half a soaked bean. Is a protein 
present ? 

B. Albuminoids or Gelatinoids (Soluble in Hot Water, Forming Jellies 
on Cooling). 

Collagen is the protein found in cartilage, skin, and bones. 

1. (Instructor's experiment.) Boil for some time a soup 
bone (chiefly tendons and bone). Strain off the clear liquid 
and cool it. A jelly is formed. 

2. Soak bones in hydrochloric acid for 2 or 3 days or a 
week. Neutralize the acid with sodium carbonate. Then 
boil the soft bone. Allow to cool. A jelly is formed. Com- 
mercial gelatine is made from bones. 

Keratin is a very insoluble protein containing much sul- 
fur. Found in hair, hoofs, and nails. 

3. Burn some hairs or feathers and note the odor. 

4. Boil some hair or feathers with strong NaOH. Add 
sodium plumbite solution. A black precipitate of lead 
sulfide shows the presence of sulfur in keratin. 

XI. DIGESTION OF FOOD 

The body is composed of water, proteins, fats, and mineral 
matter. The average daily ration contains about 100 grams 
of protein, 100 grams of fat, and 420 grams of carbohydrates, 



DIGESTION OF STARCH 103 

and over a liter of water. Before the proteins of food can 
enter the blood to build the body, they must be dissolved. 
Before the fats can enter the blood, they must be emulsified 
or saponified. Before the carbohydrates can enter the 
blood to furnish heat and energy to the body, they have to 
be dissolved and changed to simple sugars. These changes 
in the food we eat are brought about by various juices in 
the digestive tract. The process is called digestion. 

In the study of the digestion of foods the following books 
are suggested for reference. 

1. Appendix in this manual 

2. Halliburton, Physiological Chemistry. 

3. Snell, Elementary Household Chemistry. 

4. Hawk, Practical Physiological Chemistry. 

5. Hutchison, Food and Dietetics. 

6. Mathews, Physiological Chemistry. 



EXPERIMENT 45 
Digestion of Starch 

Materials. Red litmus paper, Fehling's solution, iodine solu- 
tion, clean, freshly prepared corn starch paste, pancreatin, bile 
(oxgall), sodium carbonate solution. 

Apparatus Test tubes, thermometer (Fahrenheit or centi- 
grade), tireless cooker. 

A. Action of Saliva on Cooked Starch. 

1. Allow some clear saliva to run from the mouth into a 
clean test tube. Place a piece of red litmus paper in the 
mouth, and while holding it there test the saliva in the test 
tube with Fehling's solution. Result? 



104 DIGESTION OF FOOD 

2. Now remove the litmus paper from the mouth. Is 
saliva alkaline or acid? 

3. Test 1 cc. of freshly prepared corn starch paste with 
Fehling's solution. Result? 

4. Now put about half a teaspoonful of the same paste 
in the mouth and hold it for a minute. Chew it in order 
that the starch may be well mixed with the saliva. Note 
that the taste becomes sweet. 

5. Put the paste from the mouth into a test tube. Add 
Fehling's solution and boil. Result? What is the effect 
of saliva on boiled starch ? 

6. What is the source of the saliva ? What is the ferment 
in the saliva that changes the starch? Will this ferment 
act upon uncooked starch or upon cellulose ? 

B. Action of Pancreatic Juice on Starch. (Instructor's Experiment.) 

The pancreatic juice comes from the pancreas. It acts 
in the small intestine in an alkaline solution. The ferment 
in the pancreatic juice that acts upon starch is amylopsin. 

1. Dissolve 3 grains of pancreatin in 100 cc. of lukewarm 
water. Test 3 cc. with iodine and with Fehling's solution. 
Result? 

2. Dissolve 3 grams of bile (ox gall) in 100 cc. of luke- 
warm water. Test 5 cc. with iodine and with Fehling's solu- 
tion. Result? 

3. Obtain three test tubes. To test tube No 1 add 5 
cc. of starch paste and 20 cc. of pancreatin solution. To 
No. 2 add 5 cc. of starch paste and 20 cc. of bile solution. 
To No. 3 add 5 cc. of starch paste, 5 cc. of bile, 15 cc. of 
pancreatin, and 5 cc. of dilute sodium carbonate. Keep all 
the tubes in a water bath at a temperature of 98° F. or 



DIGESTION OF PROTEINS 105 

36.6° C. (temperature of the normal human body) for 24 
hours. This can be satisfactorily done by means of a tireless 
cooker. 

4. Remove the tubes. Test the contents of each for 
starch by the iodine solution and for sugar by means of the 
Fehling's solution. In which case was digestion most com- 
plete? Why? 

Questions 

1. You eat a piece of -cake. Explain all the changes the 
starch undergoes before it is ready for the blood. 

2. Explain what changes cane sugar must undergo before 
it is digestible. (See Appendix.) 

3. Of what use are carbohydrates to the body? 

EXPERIMENT 46 
Digestion of Proteins 

Materials. Minced egg albumen from a hard-boiled egg, pepsin 
solution prepared by dissolving 1 g. of pepsin in 500 cc. of 
water, 5 N solution of HC1, pancreatin solution prepared by dis- 
solving i g. of pancreatin in 500 cc. of water, sodium carbonate 
solution made by dissolving 1 g. of sodium carbonate in 100 
cc. of water. 

Apparatus. Test tubes, thermometer, tireless cooker or water 
oven. 

A. Action of Gastric Juice. (Instructor's Experiment.) 

The saliva has no action on proteins. The gastric juice 
comes from the walls of the stomach. It consists of water, 
acids (hydrochloric acid chiefly), and several ferments. The 
ferments that act upon protein are rennin and pepsin. 

1. What is the action of hydrochloric acid upon dissolved 



106 DIGESTION OF FOOD 

proteins like casein and albumen in milk ? (Recall Experi- 
ment 43, B, 2.) 

2. What is the action of rennin upon such proteins ? (See 
also Experiment 43, B, 2.) 

3. Mince well in a clean mortar the coagulated egg al- 
bumen of a hard-boiled egg. In each of 4 test tubes place 
about 3 grams of egg albumen. To tube No. 1 add 20 cc. 
water. To test tube No. 2 add 20 cc. hydrochloric acid. 
To No. 3 add 20 cc. of the pepsin solution. To No. 4 add 
10 cc. of hydrochloric acid and pepsin. 

4. In a fifth test tube place a lump of egg albumen. Add 
10 cc. of hydrochloric acid and pepsin. This is tube No. 5. 
Label each tube and keep them all at a temperature of 98° F. 
(about 37° C.) for 24 hours. To do this put them in a water 
bath in a fireless cooker or in a water oven. 

5. In which tube is the egg albumen most completely 
liquefied or digested ? To what may some of the cases of 
indigestion be due ? 

6. Compare tubes No. 4 and No. 5. How is the diges- 
tion of proteins affected by insufficient mastication ? 

B. Action of the Pancreatic Juice. 

The ferment in the pancreatic juice which acts upon pro- 
teins is trypsin. It acts in an alkaline solution in the small 
intestine. 

1. In each of 3 other test tubes place 3 grams of the 
minced egg albumen. Number these test tubes No. 6, 
No. 7, and No. 8 respectively. To No. 6 add 10 cc. of 
pancreatin solution and 10 cc. of the hydrochloric acid. 
To No. 7 add 10 cc. of pancreatic and 10 cc. of the sodium 
carbonate solution. Put these tubes into the same water 



FOOD ANALYSIS 107 

bath at 98° F. or 37° C. for 24 hours. To No. 8 add only 
pancreatin solution. 

2. Note results in Nos. 6, 7, and 8. In which tube is 
digestion most complete ? 

Questions 

1. If you drink a glass of milk, explain all the changes 
the casein will undergo before it enters the blood. Tell 
where each change takes place, and the name of the ferments 
causing it. 

2. Of what use are proteins to the body? 

3. Explain how fats are digested. (See Appendix.) 

4. Of what use are fats to the body ? 

5. How are the sugars (disaccharids) digested? (See 
Appendix.) 

6. Of what use are the sugars to the body ? 

7. If you eat ice cream explain completely the digestion 
of fat, the cane sugar, and the milk sugar. 

XII. FOOD ANALYSIS 

It would be impossible in a course of this kind to take up 
in detail the analysis of many foods. Milk is the most 
common food and possibly the one most subject to adultera- 
tion and contamination. Its composition and method of 
analysis should be understood. 

Books of reference : 

1. Olsen, Pure Foods. 

2. Leach, Food Inspection and Analysis. 

3. Sherman, Food Products. 

4. Wing, Milk and Its Products. 

5. Woodman, Food Analysis. 



108 FOOD ANALYSIS 

EXPERIMENT 47 
Analysis of Milk 

Materials. Whole milk, skimmed milk, dilute hydrochloric 
acid, litmus, rennin or junket tablets, Fehling's solution. 

Apparatus. Hydrometer, lactometer, hydrometer jars, evaporat- 
ing dish, balance, centrifugal machine. 

A. Specific Gravity of Milk. (Instructor's Experiment.) 

1. Test the specific gravity of water, whole milk, and 
skimmed milk with a hydrometer. Which is the heaviest 
per unit volume ? Which is the lightest ? 

2. Test the specific gravity of water, whole milk, and 
skimmed milk with a lactometer. Could water be added 
to skimmed milk till its specific gravity was that of whole 
milk? Try it. 

B. Water in Milk. (Student's Experiment.) 

1. Weigh an evaporating dish on a balance. Pour about 
20 cc. of whole milk into the dish and weigh again. What 
is the weight of the milk? Heat the milk gently until all 
the water is evaporated. Do not let it char. Weigh the dish 
with the residue. Calculate the per cent of water in milk. 

2. Tabulate your data thus : 

(a) Weight of empty dish = g. 

(6) Weight of dish plus milk before evaporating water = g. 

(c) Weight of dish plus residue after evaporating water = g. 

(&) — («) = g., weight of milk used 

(6) — (c) = g., weight of water in milk 

3. Calculate the per cent of water thus : 
Weight of water ~ weight of milk 

Xl00 = % water in milk. 

What is the correct per cent of water in milk? 



ANALYSIS OF MILK 109 

C. Total Solids in Milk (Albumen, Casein, Lactose, Fats, Mineral 
Matter). 

1. From the data in B, 2 above calculate the per cent of 
total solids in milk, thus : 

(6) — (a) = g., weight of milk used 

(c) — (a) = g., weight of residue or total solids 

Then, weight of total solids -r weight of milk X 100 = 

■ % of total solids in milk. 

2. What is the correct per cent of solids in milk ? 

3. If the per cent of total solids is less than 12%, what 
does it indicate ? 

D. Mineral Matter in Milk. 

1. Ignite the residue that remains after evaporating the 
water in (B) until only a white ash remains. What sub- 
stances in the residue will burn ? 

2 Weigh the dish plus ash and call this (d). 

3. Determine the per cent of ash thus : 

(6) — (a) = g., weight of milk used 

(d) — (a) = g., weight of ash 

Weight of ash -s- weight of milk X 100= % of ash 

4. What is the correct per cent of ash in milk ? 

5. What is the ash in milk chiefly? 

E. Fats in Milk. (Instructor's Experiment.) 

1. Milk is an emulsion. The small particles of butter 
fat are held in suspension by the milk albumen and casein. 
If fresh milk is allowed to stand in a cool place, the butter 
fat rises, forming a layer of cream. This is the gravity 
method of separating cream from milk. 

2. In dairies the cream is separated from the milk more 
completely and more quickly by the centrifugal cream sepa- 



110 FOOD ANALYSIS 

rator. Show the principle of the separator by filling the 
tubes of a centrifugal machine with whole milk. Operate 
the machine for five minutes and note the layer of cream in 
the tubes. 

3. If there is a Babcock milk-testing machine in the labor- 
atory, determine the per cent of butter fat in whole milk. 
(See Experiment 48.) 

4. What is the usual per cent of fat in milk ? 

5. What per cent is required by law in the city ? 

F. Albumen in Milk. (Student's Experiment.) 

1 . How would you show the presence of albumen in milk ? 
Recall Experiment 43, A, 7. 

2. What is the per cent of albumen in milk? 

G. Casein in Milk. 

1. To half a test tube of skimmed milk add dilute hydro- 
chloric acid or any dilute acid. Warm. W r hat is the coagu- 
lated mass ? Recall Experiment 43, B, 2. 

2. Test milk with litmus. Result? Now let it stand in 
a warm place for two or three days till it is thick. Taste 
it, smell it, and test with litmus. Some of the lactose is 
changed to lactic acid, which coagulates the casein. 

3. Warm 50 cc. of milk in your evaporating dish. Add 
a little "rennin" or "rennit" or a piece of "junket tablet" 
about the size of a pin head. Stir till it is dissolved, then 
cool it. Result ? Keep this for H. 

4. What is the per cent of casein in milk ? 
H. Lactose, the Sugar in Milk. 

1. Warm the coagulated casein obtained in G, 3 above, 
then filter the "curd." The greenish liquid obtained as 
the filtrate is called " whey.:* 



BABCOCK TEST FOR BUTTER FAT IN MILK 111 

2. Add Fehling's solution to some "whey." Boil. Is 
lactose present ? 

3. What is the per cent of sugar in milk? 

Questions 

1. What is the average composition of cow's milk? 

2. Is milk a perfect food for an adult ? Why? 

3. What is butter? 

4. What is buttermilk? 

5. What is cottage cheese ? 

6. How is the ordinary grocery or "eheddar" cheese 
made? 

7. What is evaporated milk? 

8. What is ice cream? 

EXPERIMENT 48 
Babcock Test for Butter Fat in Milk 

Note : Four varieties of test bottles are used as follows : 

a. for whole milk, graduated for 8 % to io %. 

b. for ordinary cream, graduated for about 30 %. 

c. for whipping cream, graduated for 50 %. 

d. for skimmed milk, graduated for .5 %. 

Materials. Bottle of whole milk, concentrated sulfuric acid, 
skimmed milk, canned milk, ordinary cream, whipping cream. 

Apparatus. Babcock test bottles as indicated above, Babcock 
tester, pipette. 

A. Whole Milk. 

1. Thoroughly mix the entire bottle or can of milk by 
pouring back and forth into a beaker several times. 

2. Using the pipette, measure 17.6 cc. and deliver into the 
test bottle a (for whole milk). Incline the test bottle so 



112 FOOD ANALYSIS 

that the milk will run down one side of the narrow neck while 
air passes out the other side, to avoid bubbling and loss of 
milk. 

3. Add 17.5 cc. of concentrated sulfuric acid, inclining the 
test bottle as before and revolving it slowly so that all parts 
of the neck have the milk washed down. 

4. The acid sinks to the bottom. Mix acid and milk 
by revolving and gentle shaking, being careful not to throw 
clots back into the neck. The acid dissolves all but the fat 
and the contents turn dark brown and get hot. 

5. Put the bottle into the Babcock testing machine. 
Fill all the pockets with bottles of milk to be tested or fill 
the opposite bottles to balance the machine. 

6. Whirl 5 minutes at the required speed (80 turns per 
minute usually). Add hot water to fill the neck of the test 
bottle. Whirl 2 minutes more. 

7. Add hot water to drive all the fat into the neck of the 
test bottles, but not above the graduations. Whirl one 
minute more. 

8. Read the per cent of fat from the graduated neck while 
still hot. What is the per cent of butter fat in the sample 
of whole milk? 

B. Ordinary Cream. 

1. Put empty test bottle b on the scales. Weigh it. Add 
just 18 grams of thoroughly mixed cream. This is about 
the amount of cream that the 17.6 cc. pipette will deliver. 
9 grams of cream may be used and the result multiplied 
by 2. 

2. Add acid and proceed as for milk. What is the per 
cent of butter fat in ordinary cream ? 



BEVERAGES— TEA, COFFEE, COCOA 113 

C. Whipping Cream. 

1. Put empty test bottle c on the scales and proceed as 
for ordinary cream. 9 grams may also be used and the per 
cent multiplied by 2. What is the per cent of butter fat in 
whipping cream ? 

D. Skimmed Milk. 

1. Use test bottle d with two necks, the larger to deliver 
materials into the smaller, to read the fractions of per cents 
as the fat rises. What is the per cent of butter fat in skimmed 
milk? 

E. Canned Milk. 

1. Pour out entire contents of the can and mix well. 

2. Weigh 9 grams into test bottle a. Add 9 cc. of water. 
Mix thoroughly in the test bottle. Add enough concen- 
trated sulfuric acid to turn the contents dark brown. Pro- 
ceed as before. ' 

3. If the canned milk is sweetened special precautions 
may be necessary. (See Leach.) What is the per cent of 
butter fat in the milk tested ? 

EXPERIMENT 49 

Beverages — Tea, Coffee, Cocoa 
References : 

1. Olsen, Pure Food, pages 110-112. 

2. Sherman, Food Products, pages 465-466. 

3. Bailey, Sanitary and Applied Chemistry, Chapter XXII. 

Materials. Tea, coffee, chocolate, cocoa, ferric chloride, 
chloroform, iodine solution, sulfuric acid, Fehling's solution, 
Millon's reagent. 

Apparatus. Beakers, funnels, filter paper, test tubes, graduate, 
teaspoons, tablespoons, separatory funnel 



114 FOOD ANALYSIS 

Tea 

A. Tannin in Tea. 

1. Boil 50 cc. of water in a beaker. Add a level tea- 
spoonful of tea and remove from the flame at once. Allow 
it to stand just five minutes, then filter. Place 5 cc. of the 
filtrate in a test tube, add 1 cc. of ferric chloride, 25 cc. of 
water from your graduate. Stir. Keep this test for com- 
parison. What is the dark precipitate? 

2. To 50 cc. of boiling water in the beaker add a level 
teaspoonful of the same tea and boil for five minutes, then 
filter. Place 5 cc. of the filtrate in a test tube of the same 
size as that used in A, 1. x\dd 1 cc. of ferric chloride solu- 
tion and then 25 cc. of water. Stir. Compare the intensity 
of color with that of A, 1 and explain. What is the best 
method of preparing tea ? Why ? 

B. Theine or Caffeine in Tea. (Instructor's Experiment.) 

1. Boil three teaspoonfuls of good tea in 100 cc. of water 
for five minutes, filter, cool, and add 20 cc. of chloroform. 
Place the mixture in a separatory funnel, shake well for one 
minute, and then allow the chloroform to settle. Draw it 
off into a clean beaker and allow it to evaporate at room 
temperature. Note the pleasant smelling, silky crystals 
of theine or caffeine. (They are the same chemically.) 

C. Questions on Tea. 

1. How is green tea prepared for market? Name some 
varieties of green tea on the market. 

2. How does black tea differ from green tea ? Name some 
varieties of black tea on the market. 

3. Which contains more tannin, the black or the green 
tea ? Give the reason for vour answer. 



BEVERAGES— TEA, COFFEE, COCOA 115 

Coffee 

D. Tannin in Coffee. 

1. To 200 cc. of cold water in your large beaker add one 
tablespoonful of well-ground coffee. Slowly bring this to 
the boiling point and boil for three minutes. Filter. Treat 
5 cc. of the filtrate as in A, 1. Keep the test for comparison. 

2. Repeat D, 1, but boil for fifteen minutes. Filter and 
treat 5 cc. of the filtrate as in A, 1. Compare the intensity 
of color with that of D, 1 and explain. What is the best 
method of preparing coffee? Why? 

E. Caffeine or Theine in Coffee. (Instructor's Experiment.) 

1. Add two tablespoonfuls of coffee to 250 cc. of cold 
water. Bring slowly to the boiling point and boil five min- 
utes. Filter. Cool the filtrate and repeat B, 1. Note 
the pleasant smelling, silky crystals of caffeine or theine. 
What is the effect of caffeine or theine upon the human 
system ? 

F. Questions on Coffee. 

1. How is coffee prepared for market? 

2. Why is the coffee bean roasted? 

Chocolate and Cocoa 

G. Fat in Chocolate and Cocoa. 

1. Test both chocolate and cocoa for fat by treating 10 
grams of each with 50 cc. of gasoline. Shake well and filter 
through a dry filter. Allow the gasoline to evaporate. 
Which contains the most fat? 

H. Questions on Chocolate and Cocoa. 

1. How is chocolate prepared from the bean for market? 

2. How is the beverage made from chocolate? 



116 FOOD ADULTERANTS 

3. How does the preparation of cocoa on the market 
differ from that of chocolate? 

4. Which beverage is the more nourishing, chocolate or 
cocoa ? Why ? 

5. For what other purposes are chocolate and cocoa used? 

Note: If possible visit a manufacturing house where chocolate and cocoa 
are prepared from the unroasted beans. 



XIII. FOOD ADULTERANTS 

The most important food adulterants may be divided 
into three classes : (1) Substitutes. (2) Artificial Coloring. 
(3) Preservatives. 

References : 

1. Leach, Food Inspection and Analysis. 

2. E. M. Bruce, Detection of the Common Food Adulterants. 

3. Woodman, Food Analysis. 

4. Olsen, Pure Foods. 



EXPERIMENT 50 

Adulterants in Milk 

Materials. Milk containing borax or boric acid, another sample 
containing formaldehyde, limewater, hydrochloric acid, turmeric 
paper, ferric ammonium alum, concentrated sulfuric acid. 

Apparatus. Evaporating dish, test tubes. 

A. Substitutes. 

1. Cream may be removed and water added until the 
specific gravity is that of pure whole milk. What should 
be the per cent of water in whole milk? How can the per 
cent of water in milk be determined? (See Experiment 47.) 



ADULTERANTS IN MILK 117 

B. Artificial Coloring. 

Milk is seldom colored artificially. Annatto or turmeric 
might be used as in the case of butter and they would be 
detected in the same way. 

C. Preservatives. 

1 . Borax and boric acid in milk may be detected as follows : 
Place 20 cc. of milk in an evaporating dish. Add 5 cc. of 
limewater. Evaporate to dryness. Continue to heat the 
dish till only a white residue remains. If borax or boric 
acid was in the milk it will be present in this ash. Dissolve 
the residue in 1 cc. of dilute hydrochloric acid. Dip a strip 
of turmeric paper in the solution and dry at 100° on a test 
tube of boiling water. A bright red color indicates the 
presence of boric acid or borax. The red color is changed 
to dark green by a drop of ammonium hydroxide. 

If there is much borax or boric acid present, the test may 
be simplified. Acidify the milk with hydrochloric acid. 
Dip in the turmeric strip. Dry at 100° on a test tube of 
boiling water. A bright red color will appear. 

2. Formaldehyde in milk may be detected as follows : 
Dissolve a crystal of ferric ammonium alum (about the 
size of a pea) in about 1 cc. of "water. Carefully add 
1 cc. of concentrated sulfuric acid. Pour this solution 
carefully down the side of an inclined test tube contain- 
ing about 10 cc. of the milk to be tested. A violet colora- 
tion is produced at the junction of the two liquids if 
formaldehyde is present. Warm over the Bunsen burner 
if necessary. 

If possible visit a large dairy or creamery and note par- 
ticularly the precautions taken for the sake of cleanliness. 



118 FOOD ADULTERANTS 

EXPERIMENT 51 
Test for Adulterants in Butter 

Materials. Pure butter, oleomargarine, ice water, sweet milk, 
carbon disulfide, ethyl alcohol, hydrochloric acid, ammonium 
hydroxide, concentrated sulfuric acid, white woolen yarn, tur- 
meric paper. 

Apparatus. Test tubes, beakers, pine splints. 

A. Detection of Substitutes. 

1 . In two separate test tubes place 5 grams of pure butter 
and 5 grams of oleomargarine or renovated butter. Heat 
each over the Bunsen burner. The pure butter melts 
quietly, producing much foam, while the renovated butter 
or oleomargarine sputters and crackles and produces very 
little foam. This is called the foam test for butter. 

2. In two separate small beakers place 5 grams of pure 
butter and of oleomargarine. Add to each about 25 cc. of 
sweet milk and warm gently till the samples are melted. Then 
place the beakers in ice water and stir constantly with pine 
splints till the fat solidifies. In the case of oleomargarine 
the fat will collect in a lump which may be lifted out by the 
stick, while pure butter or renovated butter will form an 
emulsion with the milk resembling cream. 

3. Given an unknown sample, how would you proceed 
to determine whether it was oleomargarine, renovated but- 
ter, or real butter ? 

B. Detection of Artificial Coloring in Butter. 

1. To 5 grams of butter in a large test tube add 4 grams 
of carbon disulfide and 30 grams of ethyl alcohol. Shake 
well and allow the mixture to stand till it separates into 



TEST FOR ADULTERANTS IN BUTTER 119 

two layers. The lower layer is the carbon disulfide contain- 
ing the butter fat in solution. The upper layer is alcohol, 
which dissolves the dye and is colored by it. If the alcohol 
layer is colorless, the butter contains no artificial coloring. 

If the alcohol layer is colored, test for artificial dyes as 
follows : 

2. Turmeric : To 5 cc. of the alcohol layer add ammonium 
hydroxide. If a brown color is produced, turmeric was used 
to color the butter. 

3. Annatto : Evaporate 10 cc. of the alcohol layer to 
dryness with a low Bunsen flame. Add a drop of concen- 
trated H 2 S0 4 to the residue. A greenish blue coloration 
indicates the presence of annatto. 

4. Coal-tar dyes : To 10 cc. of the alcohol extract add 10 
cc. of water. Add 1 cc. of HO and a piece of white woolen 
yarn. Boil. If the yarn is colored the presence of coal-tar 
dyes is shown. 

C. Preservatives in Butter. 

1. The preservative most often used is boric acid. To 10 
grams of butter add 10 cc. of water and boil. Pour off the 
melted fat. To the water remaining add 1 cc. of HC1. Dip 
a strip of turmeric paper into the solution and dry on a test 
tube of boiling water. A cherry red color denotes the pres- 
ence of boric acid. Add a drop of ammonia to the colored 
paper. Result ? 

Questions 

1 . How is pure butter made ? 

2. What is "renovated butter"? 

3. What is oleomargarine ? 



120 FOOD ADULTERANTS 

EXPERIMENT 52 
Adulterants in Jellies and Candies 

Materials. Jellies, candies, iodine solution, acid mercuric ni- 
trate (see Appendix), picric acid solution, AN hydrochloric 
acid, white woolen yarn or strips of white woolen cloth. 

Apparatus. Test tubes, beakers. 

A. Substitutes. 

1 . Starch : Boil about 5 grams of jelly with water, cool, and 
add a solution of iodine. The usual dark blue color indicates 
the presence of starch. 

Test cheap candies for starch. 

2. Gelatin: Put 1 cc. of jelly in a test tube. Add 10 cc. 
of water. Warm till the jelly is dissolved. Cool. Add 
an equal volume of acid mercuric nitrate and 20 cc. of cold 
water. Shake well and allow it to stand for five minutes. 
Filter. If gelatin is present the filtrate will be cloudy. 
To confirm the test add 1 cc. of saturated water solution of 
picric acid to a portion of the filtrate. If gelatin is present, 
a yellow precipitate will be formed. Test candy in the same 
way. 

B. Artificial Coloring. 

Artificial jams and jellies are often colored with anilin 
dyes to imitate the natural fruit product, therefore a test for 
the dyes indicates the character of the product. 

1. Dissolve about 15 grams of the jelly in 100 cc. of water. 
Filter if necessary. Add 1 cc. of 4 N hydrochloric acid. Place 
in it strips of white woolen cloth or woolen yarn and boil 
for five minutes. Now remove the strips and wash them in 
cold water and then boil again in a very dilute solution of 
hydrochloric acid. If the strip has a dull color the coloring 



ADULTERANTS IN JELLIES AND CANDIES 121 

matter in the jelly was due to the natural coloring in the fruit. 
If the strip is brightly colored, anilin dyes were present. 
Paste the strip in the notebook. 

2. In like manner test candies for the presence of anilin 
dyes. Paste the strip in the notebook. 

C. Preservatives. 

1 . Candies and jellies are naturally preserved by the sugar 
present. 

2. By what four methods may foods be preserved? 

3. Describe briefly each method. 

4. Which methods are harmless ? 

5. Which are not? Why? 

6. How are pure jellies prepared ? 

7. How are pure candies prepared ? 

XIV. FOOD VALUES 

Food is any substance which when taken into the body 
supplies it with heat and energy or builds tissue. 

There are five classes of food principles : proteins, fats, car- 
bohydrates, mineral matter, and water. Proteins, mineral 
matter, and water are the tissue builders. Fats and carbo- 
hydrates furnish heat and energy. Proteins, fats, and carbo- 
hydrates are called the nutritive constituents of foods. 

These nutritive constituents oxidize or burn in the body 
and produce heat. The amount of heat so produced has 
been found to be the same as the heat produced by the 
substances if burned outside the body in the laboratory. 
When burned in the laboratory the heat produced is meas- 
ured in calories. A calorie is the amount of heat necessary 
to raise a kilogram of water 1° C. (large calorie). 



122 



FOOD VALUES 



In the back of this Manual, you will find approximately 
the food value in calories necessary for a girl (woman) of 
your weight. There are also tables showing the portion of 
ordinary foods that contain 100 calories of heat. 



EXPERIMENT 53 

Menu Making 
A. Daily Menu. 

1. From the Appendix find the calories (food units) re- 
quired for your weight, calories furnished by protein, fat, and 
carbohydrate. 

2. One fourth of this amount should be furnished by the 
breakfast, one fourth by the lunch, and one half by the dinner. 

3. Now prepare a menu for a day for yourself, using the 
following as a model : 

Daily Menu 

Weight 159 lb. requires 239 calories protein, 717 calories 
fat, 1434 calories carbohydrate, total 2390 calories, J for 
breakfast, \ for lunch, \ for dinner. 



Meals 


Calories 
Protein 


Calories 
Fat 


Calories 
Carbohydrates 


Total 
Calories 


Breakfast 

Lunch 

Dinner 

Total calories 


61 

58 

120 

239 


176 
175 
350 
701 


350 

360 

725 

1435 


587 

593 

1195 

2375 



B. Dinner Menu. 

1. Make a dinner menu giving careful attention (a) to 
the correct number of calories as found in A, and (b) to 
the current market prices of foods, making the total cost of 
the dinner as low as possible. Tabulate as follows : 



PRODUCTS OF YEAST FERMENTATION 

Dinner Menu 



123 



Food 


Portion 


Ounces 


Cost 


Calories 
Protein 


Calories 
Fat 


Calories 
Carbohy- 
drate 


Lamb, leg, 
roasted, 
etc. 
Total 


Ord. serving 


1.8 


.05 


40 


60 


00 



XV. LEAVENING AGENTS 

A leavening agent is a substance which, when put into a 
dough, usually forms carbon dioxide. This gas "lightens" 
the dough. 

Yeast is the oldest leavening agent. It changes starch 
and sugar to carbon dioxide and alcohol. 

Baking soda is sodium bicarbonate, NaHC0 3 . It may be 
used in dough with some substance that contains an acid, 
such as sour milk or molasses. Baking powder is a mixture 
of powdered sodium bicarbonate with a powdered acid or 
acid principle, such as tartaric acid or an alum, with starch to 
keep the mixture dry. 

EXPERIMENT 54 
Products of Yeast Fermentation 

Materials. Yeast cake (compressed), molasses, limewater. 
Apparatus. 250 cc. flasks, test tube, delivery tube, distilling 
flask, condenser, thermometer, liter beaker. 

A. Carbon Dioxide. 

Note : Two students work together. 

1. Mix about one fourth of a cake of compressed yeast 
with 15 cc. of water in the evaporating dish. Stir till a 



124 LEAVENING' AGENTS 

smooth mixture is formed. Pour the yeast mixture into a 
flask containing 25 cc. of molasses and 100 cc. of water. 

2. Note the odor and taste of the mixture. 

3. Fit a one-holed stopper and a delivery tube to the flask 
containing the mixture. Let the other end of the delivery 
tube dip into a flask containing limewater. 

4. Put the flasks in the sun or a warm place. 
Begin Experiment 55. 

5. At the end of two hours examine the liquid and lime- 
water. Is the yeast working ? What gas caused the change 
in the limewater? Write the equations and name all sub- 

C0 2 +Ca(OH) 2 — ^ CaC0 3 +H 2 

6. What effect has a very low temperature upon fermen- 
tation ? Why are fresh vegetables, fruits, milk, and butter 
kept in a refrigerator ? 

7. Boil 10 cc. of the fermenting yeast mixture. Cool 
again to room temperature. Does fermentation continue? 
Why? Why do jars of canned fruit sometimes ferment? 
If these fruits are reheated soon after fermentation begins, 
they may be used. Why ? 

B. Alcohol. 

1. At the end of 12 hours examine the mixture. Has 
fermentation ceased ? Why ? 

2. Note the odor and taste of the mixture. What new 
substance is present ? The sugar in the molasses is changed 
to alcohol and carbon dioxide. Write the equation and 
name all substances. 

C 6 H 12 6 +yeast— ^2 C 2 H 5 OH+2 C0 2 



BAKING SODA, BAKING POWDER 125 

Note : Empty the mixture in your flask into the liter beaker provided. The 
teacher will distill half of this for alcohol, the other half should be labeled 
and set aside for a week or more for part C. 

3. (Instructor's experiment) : 

Distill about 500 cc. of the fermented molasses, using a 
water bath. Collect the fraction that comes over below 
79° C. What is this distillate chiefly? 

4. Note the odor of the distillate. 

5. Apply a lighted match to 1 cc. of it. Does it burn? 

6. What is formed when fruit juices containing sugar 
ferment? Where does the yeast that causes the fermenta- 
tion come from ? 

7. How does yeast leaven bread dough ? 

C. Vinegar. 

1. Note the odor and taste of the yeast molasses mixture 
that has been allowed to stand for several weeks. What is 
the substance ? 

2. How could vinegar be made at home from fruit parings ? 

3. What is "sweet cider"? 
What is "hard cider"? 
What is "cider vinegar"? 

EXPERIMENT 55 
Baking Soda, Baking Powder 

Materials. Dilute hydrochloric acid, sulfuric acid, sodium bi- 
carbonate, molasses, sour milk, powdered tartaric acid, cream 
of tartar, acid calcium phosphate H 4 Ca(P0 4 ) 2 , ammonium 
alum, any baking powder (composition unknown to student), 
6 common baking powders with labels, iodine solution, barium 
chloride solution, ammonium molybdate solution. 

Apparatus. Test tubes, beakers, funnel, filter paper. 



126 LEAVENING AGENTS 

A. Baking Soda (Sodium Bicarbonate, NaHC0 3 ). 

1. Put 15 cc. of dilute hydrochloric acid in a beaker. 
Add 1 gram of sodium bicarbonate. What gas is evolved? 
Write the equation, naming all substances : 

HCl+HNaCOs — >- NaCl+C0 2 +H 2 

2. Dissolve 5 cc. of molasses in 15 cc. of water in a beaker. 
Add 1 gram of sodium bicarbonate. Result? What is the 
acid in molasses? 

3. Repeat (2), using sour milk. Result? What is the 
acid in sour milk ? 

4. How is "soda" used to leaven a dough? 

B. Baking Powders. 

1. Tartrate baking poivders. 

a. Make a tartrate baking powder by mixing a gram of 
tartaric acid (H2C4H4O6) with a gram of sodium bicarbonate 
(NaHC0 3 ). Add 15 cc. of water. Result? What is the 
gas evolved ? Write the reaction and name all substances : 

H 2 C4H 4 6 +2 NaHC0 3 — >- Na 3 C 4 H 4 6 +2 H 2 0+2 C0 2 

b. Make a tartrate baking powder by mixing cream of 
tartar (acid potassium tartrate, HKC 4 H 4 6 ) with the soda. 
Add water as before. Result? Write the equation and 
name all substances : 

HKC 4 H 4 6 +HNaC0 3 — ^ KNaC 4 H 4 6 +H 2 0+C0 2 

2. Phosphate baking powders. 

Repeat B, 1, using acid calcium phosphate, H 4 Ca(P0 4 ) 2 , 
with the soda. Write the equation and name all substances : 

H 4 Ca(P0 4 ) 2 +2 HNaC0 3 — ^ 



HNa 2 P0 4 +HCaP0 4 +2 H 2 0+2 C0 2 



BAKING SODA, BAKING POWDER 127 

3. Alum baking powders. 

Repeat B, 1, using, instead, powdered ammonium alum, 
NH 4 A1(S04)2, with the soda. Write the equation and name 
all substances : 

2 NH 4 Al(S0 4 ) 2 +6 HNaC0 3 — >- 

2 Al(OH) 3 +(NH 4 ) 2 S0 4 +3 Na2S0 4 +6 C0 2 

4. Why is baking powder such a useful leavening agent? 

5. Which baking powder is considered most efficient of the 
three mentioned? Why? 

C. Tests for Baking Powders. 

A baking powder may be a tartrate baking powder, or 
an alum powder or a phosphate powder or a mixture of two 
or three of these powders. Test an unknown baking powder 
to determine its nature as follows : 

1. Put 15 grams of the baking powder into a beaker and 
pour over it 50 cc. of water. Stir until no more gas is 
evolved, then filter carefully. 

2. Starch is insoluble in cold water and will remain on the 
filter paper as a white residue. Make the usual starch test 
on this residue. Result? 

3. If the baking powder contains alum, the filtrate will 
contain sulfates. To 5 cc. of the filtrate add 5 cc. of hydro- 
chloric acid and 5 cc. of barium chloride solution. A white 
precipitate indicates sulfates. Is the sample an alum 
baking powder ? 

4. If the baking powder is a phosphate baking powder, 
the filtrate will contain acid calcium phosphate. Test 5 cc. 
of the filtrate for a phosphate by adding a few drops of nitric 
acid, then heat nearly to boiling and add a few drops of this 
hot mixture to 5 cc. of ammonium molybdate solution. A 



128 TEXTILES 

yellow precipitate shows the presence of phosphates. Is the 
sample a phosphate baking powder ? 

5. To test for a tartrate baking powder, pour 5 cc. of the 
filtrate into an evaporating dish- Add 5 drops of sulfuric 
acid and evaporate to dryness. Heat gently and note the 
odor of burning sugar if a tartrate is present. Is the sample 
a tartrate baking powder ? 

6. Examine labels of 6 different baking powders on the 
market and note the ingredients of each. 



XVI. TEXTILES 

The chief fibers of vegetable origin are cotton and linen. 
The important fibers of animal origin are wool and silk. 

Reference : 

1. Woolman and McGowan, Textiles. 

EXPERIMENT 56 

Cotton, Linen, Wool, and Silk 

Materials. Cotton, linen, wool, and silk textiles, 5% solution of 

KOH, concentrated HC1, Loewe's solution. 
Apparatus. Microscope, forceps. 

A. Microscopic Tests. 

1. Examine raveled samples of cotton, linen, wool, and silk 
fibers under the microscope. Draw each fiber and label it. 

B. Burning Test. 

1 . Hold a strip of wool with the forceps and ignite it in the 
Bunsen flame. Note the odor and appearance as it burns. 

2. Repeat, using strips of silk, cotton, and linen. Note 



COTTON, LINEN, WOOL, AND SILK 



129 



the odor and appearance of each as they burn. Which of 
the fibers may be detected by its odor in burning ? 

C. To Distinguish Silk and Wool from Cotton and Linen. 

1. Boil about one square inch of woolen textile in a beaker 
containing 10 cc. of a 5% solution of KOH. Result? 

2. Repeat (1), using silk, cotton, and linen in separate 
beakers. Note results in each case. 

3. Many so-called woolen textiles contain cotton. To 
detect the presence of cotton cut two samples of the material 
2 by 2 inches ; mount the first one. Boil the second sample 
for 10 minutes with a 5% solution of KOH. If the wool is 
pure, there will be no residue. If a residue is left, mount it, 
and explain the result. Record results as follows : 



Sample of wool 
used for experi- 
ment. 



Sample of same 
material boiled 
10 minutes in 
5% KOH. 



D. To Distinguish Wool from Silk. 

1. In a beaker containing 20 cc. of concentrated HC1 
place a strip of wool and one of silk and boil for two 
minutes. Which is dissolved ? 

2. Cut 2 samples of material supposed to be a mixture of 
wool and silk. Mount one sample. Treat the other as in 1. 

Pure silk will dissolve in concentrated hydrochloric acid. 
If it is weighted, a residue remains. If wool is present, 
the fibers will be undissolved. Wash, dry, and mount the 
sample, unless it is entirely dissolved. 



130 TEXTILES 



Sample of ma- 
terial used. 



Sample in con- 
centrated HC1 
for 2 minutes. 



a b 

E. To Distinguish Cotton from Silk. 

1. In a beaker containing 20 cc. of Loewe's Reagent place 
a strip of cotton and one of silk. Which fibers dissolve ? 

2. Artificial silks are usually cellulose. How would you 
distinguish real silk from artificial silk ? 

DYEING 

When a* colored substance is attached to the fibers of the 
textile in such a way that it is not removed by rubbing or 
washing or by the sunlight, the textile is dyed. 

Several of the metallic hydroxides are used as mordants 
in dyeing. They form insoluble precipitates, called lakes, 
with dyes. Wlien these lakes are formed in the fibers of the 
textile, the dye is fixed and the colors are fast. 

A dye that will dye textiles without the use of a mordant 
is called a direct dye. A dye that will not dye textiles with- 
out the use of a mordant is called a mordanted dye. 

Reference : Woolman and McGowan, Textiles. 

EXPERIMENT 57 

Textile Dyeing 

Materials. Dilute ammonium hydroxide, aluminum sulfate, 
5% logwood solution (see Appendix), alizarin, strips of cotton 
cloth 1 inch by 3 inches from which sizing has been removed 
by boiling in a 2 % solution of sodium carbonate for 5 minutes, 
Congo red solution prepared by dissolving in 200 cc. distilled 



TEXTILE DYEING 131 

water, 1 g. sodium carbonate, 2 g. sodium sulfate, and 2 g. 
Congo red. 
Apparatus. Test tubes, enameled pans or beakers for the color 
baths. 

A. Mordants and Lakes. 

1. Add 5 cc. of dilute ammonium hydroxide to 10 cc. of 
aluminum sulfate solution. The gelatinous precipitate is 
aluminum hydroxide. Write the equation for the reaction. 
Add 2 cc. of logwood solution. Shake the tube well and let 
it stand. Is the dye held by the precipitate? This colored 
precipitate is called a lake. The aluminum sulfate is a mor- 
dant. 

2. Repeat A, 1, using 2 cc. of alizarin instead of the log- 
wood solution. Let the tube stand. Result? 

B. Use of Mordants in Dyeing. 

1. Boil in a logwood solution for five minutes a strip of 
cotton cloth from which the sizing has been removed. Re- 
move, wring, and wash thoroughly. Does the color wash 
out? Dry the strip and mount it in your notebook. 

2. Mordant a piece of cotton cloth by boiling it in 20 cc. 
of aluminum sulfate solution. Wring out and let it stand 
in warm, dilute ammonium hydroxide for five minutes. 
Wring it out. 

Now boil this mordanted strip in a logwood solution for 
five minutes. Wring out and wash thoroughly. Does the 
color wash out ? 

Paste the strip in your notebook. 

3. Repeat B, 1, using an unmordanted (wet) strip in 
alizarin. Wash, dry, and mount in your notebook. 

4. Repeat 3, using a mordanted strip (wet) prepared 
as in B, 2, and alizarin. Paste the strip in your notebook. 



132 TEXTILES 

C. Direct Dye for Cotton. 

1. Place a wet piece of cotton cloth (unsized) in 20 cc. of 
prepared Congo red solution and boil 5 minutes. Remove 
the cloth, wash, dry, and mount it in your notebook. 

CLEANING OF FABRICS 

Many useful books are now on the market that explain in 
detail the removal of spots and stains from fabrics. A few 
principles of stain removing will be outlined. 

Reference : Woolman and McGowan, Textiles. 

EXPERIMENT 58 
Removing Spots and Stains 

Materials. Strips 3 inches by 4 inches of white cotton cloth 
stained with (a) blood, (b) another set of strips stained with 
coffee, (c) with spots of fruit juice, (d) with chocolate, (e) with 
grease, (/) with paint, (g) vaseline, (/?) ink stains; hydrogen 
peroxide, ammonium hydroxide, Javelle water (see Appendix), 
borax, gasoline, carbon tetrachloride, absorbent cotton or 
blotters, soap, turpentine, bleaching powder, dilute hydrochloric 
acid, oxalic acid, Ink Eradicator (see Appendix). 

Apparatus. Beakers. 

A. Stains Removed by Cold Water. 

For blood and stains of a protein nature, also for unknown 
stains, use cold water. The cloth is placed over a bowl or 
some convenient vessel and water poured first around the 
stain, then on it. 

1. Remove a blood stain by this method, or if the 
stain is old, lukewarm water and soap will remove it more 
quickly. 



REMOVING SPOTS AND STAINS 133 

B. Stains Removed by Hot Water. 

Hot water is used for colors held in a sugary solution and 
for glue. Sometimes if the stain is old, a bleach or some sub- 
stance that will react with the coloring matter should be used 
with the hot water. 

1 . Remove a coffee stain by putting the spot over a beaker 
and then pour boiling water first around the spot, then on it. 
If it is not removed, try hydrogen peroxide, alkaline with am- 
monia, on the spot ; then add hot water. Or soak in weak 
Javelle water for a few minutes and rinse with boiling water. 

2. Remove a, fruit stain by the method of B, 1. 

3. Remove a chocolate or cocoa stain by covering stain with 
borax. Soak in cold water, then pour on hot water. 

C. Stains Removed by Solvents. 

Spots produced by grease, vaseline or waxes, paint, varnish, 
or tar cannot be removed by water. Grease and waxes are 
soluble in chloroform, carbon tetrachloride, ether, gasoline, 
or benzene. Paint, varnish, or tar should be treated with 
turpentine, then with one of the solvents above. 

1. Remove a grease spot by carbon tetrachloride. Place 
absorbent cotton or a blotter under the spot and rub the sol- 
vent from the outside toward the center of the spot. Follow 
with warm soap and water. 

2. Remove a paint stain by using turpentine, then gasoline 
or carbon tetrachloride. 

3. Remove vaseline by soaking in kerosene first, then wash 
with soap and water. 

D. Stains Removed by Chemical Treatment. 

Such stains as iron rust, ink, acid stains, grass stains, and 
mildew need a special bleach or other chemical treatment. 



134 



TEXTILES 



1. Remove an ink stain, if fresh, by cold water. Or apply 
alternately solutions of bleaching powder and dilute hydro- 
chloric acid or oxalic acid. Or apply Javelle water or ink 
eradicator prepared. 

E. For the removal of other stains see the following table : 



Kind of Stain 



Fruit, tea, or coffee 



Reagent Used 

1. Boiling water, if stain is fresh. If 
old, use bleaching powder and a 
little acetic acid or hydrogen per- 
oxide and hot water. 

2. Javelle water. 

1. Alcohol or ammonia. 

2. Javelle water. 

j'l. Gasoline. f Follow with 

Grease <j 2. Carbon tetrachloride I soapsuds and 

[ [ammonia. 



Grass 



Vaseline 



Tar 



Paint 



Varnish 

Acids, hydrochloric, sulfuric 

Iron rust 



Kerosene ; follow with warm soap 
solution. 

f 1. Benzol. 
2. Turpentine ; follow with soap and 
ammonia. 

f 1. Carbon tetrachloride. 
2. Turpentine; follow with soap and 
ammonia. 

/ Equal parts of wood alcohol, benzol, 
\ and acetone. 

Ammonia in each case. 

f 1. Oxalic acid. Afterwards wash out 
acid with hot water. 
Salt and lemon juice, or citric acid. 



Ink 



Iodine 



12- 

fl- 

I 2 ' 
13. 

u. 

(i 



Sweet milk on colored goods. 

Salt and citric acid. 

Oxalic acid. 

Ink eradicator or Javelle water. 

Alcohol. 

Sodium thiosulfate. 



BLEACHING AND BLUEING 135 

Kind of Stain Reagent Used 

lyj-, , /Soapsuds. Tartaric acid followed by 

\ Javelle water. Sunlight. 

T5i i J Wash with cold or lukewarm water 

\ and soap. 

Sugar, glue Wash with hot water. 

EXPERIMENT 59 

Bleaching and Blueing 

Materials. Strips of colored calico, 3 inches by 1 inch, fresh 
bleaching powder, dilute hydrochloric acid 10%, sodium thio- 
sulfate solution, sodium sulfite, strips of colored woolen cloth, 
3 inches by 1 inch, colored feathers or ecru silk strips, 3 inches 
by 1 inch, aniline blue, oxalic acid solution 10%, sodium hy- 
droxide solution, Prussian blue, Ultramarine, Indigo. 

Apparatus. Beakers, 300 cc. bottle v/ith cork to fit. 

A. To Bleach Cotton or Linen. 

1. Obtain 2 strips of colored calico. Keep one to mount 
later and put the other in a beaker containing a thin paste 
of 5 grams of fresh bleaching powder (calcium hypochlorite) 
and 100 cc. of water. Remove the strip and dip it into a 
beaker containing 25 cc. of hydrochloric acid. Dip the strip 
into the bleaching powder again, and again into the acid till 
it is bleached. 

2. The acid liberates the chlorine from the bleaching 
powder. Write the equation. The chlorine bleaches cotton 
or linen, but it yellows wool or silk. Dip the strip into a 5% 
solution of sodium thiosulfate, which destroys the chlorine 
remaining on the cloth and prevents the fiber from being 
weakened. Wash the strip, dry it, and mount it in your note- 
book with the unbleached sample. 



136 TEXTILES 

3. Javelle water is often used for bleaching cotton or linen 
at home. It is a solution of sodium hypochlorite (NaOCl) 
and its bleaching action is similar to that of bleaching 
powder. 

B. To Bleach Wool or Straw. 

1. Put 5 grams of sodium sulfite (Na 2 S0 3 ) in a 300-cc. 
bottle and fit it loosely with a stopper. Hang a strip of 
colored woolen cloth so that it is suspended in the bottle 
when the stopper is inserted. Add 25 cc. of dilute hydro- 
chloric acid to the bottle, insert the stopper loosely, and let 
it stand. The gas liberated is sulfur dioxide. Write the 
equation. Sulfur dioxide bleaches cotton, straw, or silk as 
well as wool. Mount an unbleached and a bleached sample 
of the woolen cloth in your notebook. 

C. To Bleach Feathers, Hair, or Silk. 

1. To 10 cc. of hydrogen peroxide in a beaker add am- 
monium hydroxide little by little till bubbles of oxygen begin 
to form. Immerse a piece of ecru silk or a colored feather. 
Leave them till they are bleached. 

2. Mount the bleached and the unbleached sample. 

D. Blueing. 

In addition to bleaching, yellowish goods may be given 
a white appearance by "blueing." There are two classes 
of blueings: (1) Liquid blueings or those apparently sol- 
uble in water and sold in bottles, i.e. anilin blues and Prus- 
sian blue. (2) Solid blueings or those insoluble in water, 
i.e. ultramarine and indigo. 

1. Liquid blueing — Anilin blue. 

Obtain 10 cc. of anilin blue. To half of it add 5 cc. of 



BLEACHING AND BLUEING 137 

oxalic acid solution. The intensity of the blue color is deep- 
ened. This acid is sometimes used in the laundry. What 
harm does it do to textiles ? Add 5 cc. of sodium hydroxide 
to the other half. It usually turns red. What danger is 
there in leaving soap in the goods? The anilin blueing is 
cheap and satisfactory if used with care. 

2. Liquid blueing — Prussian blue. 

Obtain 10 cc. of Prussian blue. Add 10 cc. of dilute sodium 
hydroxide. The red or yellow precipitate is ferric hydroxide, 
which is iron rust. If soap or soda were in the clothes to 
be "blued" with Prussian blue, what would probably be the 
result ? 

3. Solid blueing — Ultramarine. 

Usually comes in balls. Obtain a portion of a ball and stir 
it in water. It is insoluble in water, but is so finely divided 
that if carefully used does not streak the goods. It is not 
affected by soap or soda. 

4. Solid blueing — Indigo. 

Usually in balls. It is expensive. It is insoluble and 
apt to streak the goods unless used carefully. It is not af- 
fected by soap or soda or light. Obtain some indigo and put 
a little into some water. Note the intense blue color. 



SOAP 

Ordinary hard soap is usually a mixture of the sodium 
salts of several organic acids, one of which is stearic acid, 
C17H35COOH. The soap sodium stearate would then have the 
formula Ci 7 H3 5 COONa. Soaps are made by the action of 
sodium or potassium hydroxide on fats. Fats are solid esters 
formed by the action of the alcohol glycerin C 3 H 5 (OH) 3 on 



138 TEXTILES 

several organic acids, one of which is stearic acid. The fat 
glyceryl stearate is (Ci7H 3 5COO) 3 C 3 H 5 . 

Reference : Any organic chemistry or any elementary 
chemistry. See also page 155 of the Appendix. 

EXPERIMENT 60 

Soaps, Cleansing Powders 

Materials. Cottonseed oil, alcohol, 40 % solutions of sodium 
hydroxide, alcoholic solution of phenolphthalein, toilet soap, 
laundry soap, solution of castile soap, calcium chloride solu- 
tions, Sapolio or other scouring soap, Dutch Cleanser or other 
cleansing powder. 

Apparatus. 500-cc. flask fitted with a one-hole rubber stopper 
and a straight glass tube 1 yard long, large evaporating dish, 
test tubes, beakers, funnel, filter paper. 

A. Preparation of Soap. (Instructor's Experiment.) 

1. Pour 50 cc. of cottonseed oil into a 500-cc. flask. Add 
100 cc. of alcohol and 15 cc. of a 40% solution of sodium hy- 
droxide. Place the stopper with the long glass tube (reflux 
air condenser) in the flask, and heat for an hour or more. 
The alcohol condenses in the tube and runs back into the 
flask. Alcohol is not needed to make soap but it dissolves 
both the oil and the hydroxide and so causes the action be- 
tween them to be more rapid. 

2. Pour the mixture into a large evaporating dish or 
enamel pan and heat till the alcohol is driven off. Stir con- 
stantly. Cool the mixture. The solid substance is soap. 
Write the equation for the making of soap. Name all sub- 
stances : 

(C 17 H 35 COO) 3 C 3 H 5 +3 NaOH 

— >■ C 3 H 5 (OH) 3 +3 C 17 H 35 COONa 



SOAP, CLEANSING POWDERS 139 

3. Shake some of this prepared soap with distilled water. 
Does it produce suds ? 

B. Properties of Soap. (Student's Experiments.) 

1. Free alkali in soap. 

Cut a piece of dry toilet soap and add to the freshly cut 
surface a few drops of an alcoholic solution of phenol- 
phthalein without water. If a red color appears, free alkali 
is present. In the same way test a piece of laundry soap 
for free alkali. Why should woolen goods not be washed 
with a soap containing free alkali ? 

2. Free fat in soap. 

Shake a few shavings of dry soap in a test tube with 20 cc. 
of gasoline. Filter into a beaker. Allow the gasoline to 
evaporate. A greasy residue indicates unsaponified fat. 

3. Water in soap. 

Place a few shavings of a fresh soap in a large test tube. 
Heat the tube gently and look for drops of water on cool 
sides of tubes. Result? Is it wise to buy a cheap, soft, 
highly scented or colored soap ? Why ? 

4. Action of soap in hard water. 

If soap is added to a solution of a calcium or magnesium 
salt, an insoluble calcium or magnesium soap is formed. 
Hard water contains salts of calcium and magnesium and such 
waters form a curdy precipitate when soap is added. 

To 20 cc. of distilled water add 5 cc. of a pure castile soap 
solution. Shake and note the suds. Now add 5 cc. of a 
solution of calcium chloride. What is the white precipi- 
tate? Shake. Are suds formed? 

Write the equation and name all substances : 

2 C 17 H 35 COONa+CaCl 2 — ^ 2 NaCl+(Ci 7 H 3 5COO) 2 Ca 



140 TEXTILES 

C. Water Softeners. 

1. When may water be made "soft" by boiling? Ex- 
plain. Write equation. 

2. Washing soda, Na^CC^, will precipitate calcium or 
magnesium salts in hard water as carbonates, thus removing 
the "hardness." Write equations to show. 

Test a soap powder for sodium carbonate by adding hydro- 
chloric acid to 5 grams in a test tube and observe efferves- 
cence. Result? Test also a hard water soap. Result? 

Note : There are many water softeners on the market ; sodium carbonate, 
sodium phosphate, or sodium silicate are often the chief constituents. The 
action of these is to precipitate the calcium or magnesium salts as insoluble 
carbonates, phosphates, or silicates. 

D. Scouring Soaps and Cleansing Powders. 

1. Boil 10 grams of a scouring soap, such as Sapolio, or 
a cleansing powder such as Dutch Cleanser, in a beaker with 
50 cc. of water. Filter. 

2. Add dilute hydrochloric acid to the residue. If it 
effervesces, insoluble carbonates are indicated. Result? 

3. The residue insoluble in dilute acid may be clay, fine 
sand, or pumice. Note your sample. 

4. Add dilute hydrochloric acid to the filtrate. Efferves- 
cence indicates sodium carbonate. Result? 



APPENDIX 

THE METRIC SYSTEM 

This is the system used by scientists. It is used by everyone 
in most of the countries of Europe and, because of its con- 
venience, is being used more and more in the United States 
and Great Britain. 

1. Length : 

The unit is the meter. It is equal to 39.37 inches or 1.1 yards. 
The centimeter is the unit of length most used by the chemist. 
It is y^-q- of a meter, or f of an inch. 

10 millimeters (mm.) = l centimeter (cm.) 
10 centimeters =1 decimeter (dm.) 

10 decimeters = 1 meter (m.) 

1000 meters =1 kilometer (km.) 

2. Volume: 

The unit used by the chemist is either the cubic centimeter or 
the liter. The volume of a flask may be given as 500 cc. or 
\ liter. One U. S. liquid quart = 946.36 cubic centimeters, a 
little less than a liter. 

1000 cubic millimeters =1 cubic centimeter (cc.) 
1000 cubic centimeters=l cubic decimeter 
1000 cubic decimeters = 1 cubic meter 

3. Weight: 

The unit is the gram. This is the weight of 1 cc. of pure water 
at its temperature of greatest density, 4° C. 

10 milligrams (mg.) =1 centigram (eg.) 
10 centigrams =1 decigram (dg.) 

10 decigrams =1 gram (g.) 

1000 grams = 1 kilogram (kg.) 

141 



142 APPENDIX 

The gram and the kilogram are the units of weight most 
generally used by the chemist. 

One ounce avoirdupois = 28.35 grams 
One pound avoirdupois = 453.59 grams 
One kilogram = 2.2 pounds 

TEMPERATURES 
Centigrade and Fahrenheit and Absolute Scales 

The Centigrade Thermometer is the one used in scientific work. 
The abbreviation for centigrade is C. The boiling point of 
water on this thermometer is marked 100 and the freezing point 
is marked 0. The 100 equal divisions between these points are 
called degrees. The abbreviation for degrees is °. The boiling 
point of water is written 100° C . Degrees below zero are written 
as minus; thus, -20° C. means 20° below zero. 

The Fahrenheit Thermometer is the one commonly used in 
this country. On this thermometer the boiling point of water 
is 212° F. and the freezing point of water is 32° F. above zero. 

To change the Fahrenheit degrees to centigrade degrees, sub- 
tract 32 and multiply the remainder by f , thus : 
C.=f (F.-32) 

To change centigrade degrees to Fahrenheit degrees multiply 
by f and add 32 to the product, thus : 
F.=f C.+32 

The Absolute Temperature is the one used by scientists in 
the study of gas volumes. 

The point -273° C. is called the absolute zero. Absolute 
temperature is reckoned from this point. Degrees on the abso- 
lute scale are found by adding 273 to the readings on the centi- 
grade thermometer. Thus : 

10°C, = 10 o +273 o = 283°T. 
-60°C.= -60 o +273 o =213°T. 



APPENDIX 



143 



LIST OF THE COMMON ELEMENTS, THEIR SYMBOLS, 
ATOMIC WEIGHTS, AND VALENCES 

O = 16 



i Name 


Sym- 
bol 


Valences 


At. 
Wt. 


Name 


Sym- 
bol 


Valences 


At. 
Wt. 


Aluminum 


Al 


3 


27.1 


Nickel . . 


Ni 


2-3 


58.7 


Antimony . 


Sb 


3-5 


120.2 


Nitrogen 


N 


3-5 


14 


Arsenic . . 


As 


3-5 


75 


Oxygen . 


O 


2 


16 


Barium 


Ba 


2 


137.4 


Phosphorus 


P 


5-3 


31 


Bismuth . 


Bi 


3 


208 


Potassium 


K 


1 


39.1 


Boron . . 


B 


3 


11 


Silicon 


Si 


4 


28.3 


Bromine . 


Br 


1-5 


79.9 


Silver . . 


Ag 


1 


107.9 


Cadmium . 


Cd 


2 


112.4 


Sodium 


Na 


1 


23 


Calcium 


Ca 


2 


40.1 


Sulfur . . 


S 


2-4-6 


32.1 


Carbon 


C 


4-2 


12 


Tin . . 


Sn 


2-4 


119 


Chlorine . 


CI 


1-5-7-3 


35.5 


Zinc . . 


Zn 


2 


65.4 


Chromium 


Cr 


3-6-7-2 


52 










Cobalt . . 


Co 


2-3 


59 










Copper . . 


Cu 


2-1 


63.6 










Fluorine . 


F 


1 


19 










Gold . . 


Au 


1-3 


197.2 










Hydrogen . 


H 


1 


1 










Iodine . . 


I 


1-5-7 


127 










Iron . . . 


Fe 


3-2 


55.9 










Lead . . 


Pb 


2-4 


207.1 










Magnesium 


Mg 


2 


24.3 










Manganese 


Mn 


2-7-4-6-3 


54.9 










Mercury . 


Hg 


2-1 


200.6 











THE WEIGHT IN GRAMS OF 1 LITER OF VARIOUS GASES 
MEASURED UNDER STANDARD CONDITION (0 DE- 
GREES C. AND 760 MM. PRESSURE) 



Acetylene 1.16 

Air 1.29 

Ammonia 0.77 

Carbon dioxide . . . . 1.98 

Carbon monoxide . . . . 1.25 

Chlorine 3.17 

Hydrogen 0.09 

Hydrogen chloride . . . 1.64 



Hydrogen sulfide .... 1.54 

Methane 0.72 

Nitric oxide 1.34 

Nitrogen 1.25 

Nitrous oxide 1-98 

Oxygen 143 

Sulfur dioxide 2.93 



144 



APPENDIX 



FOOD CHEMISTRY OUTLINE 

Compounds Found in the Body and in Foods. 

1. Definition of a food. 

2. Relation of food to the body. 

3. Chief elements found in the body and in foods are carbon, 

oxygen, hydrogen, nitrogen, sulfur, phosphorus, calcium. 

4. The elements are combined to form two classes of com- 

pounds in the body and in foods : 

f 1. Water, H 2 (65 % or more in the body). 
Inorganic < 2. Inorganic salts (mineral matter, ash, 5% in body, 
[ chiefly calcium phosphate) . 

1. Carbohydrates (less than 1 % in 
body). 

a. Starch group (C 6 Hio0 5 )n. 

1. Starch. 4. Cellulose. 

2. Glycogen. 5. Gums. 

3. Dextrin. 6. Pectin. 

b. Sugars. 

1. Sucrose group (C12H22O11). 

a. Sucrose — cane sugar. 

b. Lactose — milk sugar. 

c. Maltose — malt sugar. 

2. Glucose group (CeHioOe). 

a. Dextrose — grape 
sugar — glucose. 

b. Levulose — fruit sugar 
— fructose. 

c. Galactose from milk 
sugar. 

2. Fats (12% in body — this varies). 

a. Animal source. 

1. Milk — cream, butter. 

2. Fatty tissue — lard, tal- 
low, whale oil. 

b. Plant source. 

1. Seeds — sunflower, cot- 
ton, flax, castor bean. 

2. Nuts — coconut, almond, 
peanut. 

3. Fruit — olive, avocado. 



II. Organic 



Non-nitrogenous 
(contain carbon 
hydrogen and 
oxygen only). 





APPENDIX 






' 1. Albumens. 






a. Egg albumen. 






b. Blood albumen. 




Nitrogenous 


c. Milk albumen. 


II. Organic 
(Continued) 


Substances or 

Proteins 

(contain car- ' 
bon, hydro- 


2. Casein. 

3. Globulins. 

a. Gluten. 

b. Myosin. 




gen, oxygen, 
and nitrogen) . 


c. Legumen. 
4. Albuminoids or gelatinoids. 
a. Collagen. 
6. Keratin. 



145 



a. 



h. 



c. 



d. 



B. Inorganic Compounds. 
1. Water: 

Most abundant inorganic compound in the body. It 

forms 60 % of the body. 
Tissues in which it is most abundant : 

Blood, eyeballs, tears, digestive juices, muscle 
tissues, lymph, all the important organs of the 
body. 
Tissues in which it is the least abundant : 

Hair, teeth, bones, nails, skin, fatty tissues. 
Use of water to the body : 

It carries nourishment to and waste from living 
tissues of the body. It cleans and flushes the 
system. It regulates the temperature of the 
body. 
e. Supplied to the body : 

By drinking it pure and in all beverages such as 
milk, in soups, melons, fruits, and vegetables. 
/. Foods with much water : 
See table in Appendix. 
g. Foods with little water : 
See table in Appendix. 
h. Foods with no water : 

See table in Appendix. 



146 APPENDIX 

2. Inorganic salts (mineral matter or ash, 5% of body by 
weight) : 

a. Tissues in which it is most abundant : 

Bones — Ca 3 (P0 4 ) 2 , Mg 3 (P0 4 ) 2 , CaC0 3 , chiefly. 

Hair, nails, skin — Si0 2 , CaF 2 , chiefly. 

Muscle tissue — Na 2 Cl, Na 2 C0 3 , Na 3 P0 4 , and 

KC1, chiefly. 
Blood and all liquids in the body contain nearly the 

same salt as muscle tissue. 

b. Tissues with little if any inorganic matter : 

Fatty tissues. 

c. Use of inorganic salts to the body : 

To build tissues, aid digestion, and to stimulate the 
appetite. 

d. Foods containing much : 

See table in Appendix. 

e. Foods with little or none : 

See table in Appendix. 

C. Organic Compounds in the Body and in Foods. 

1. Organic compounds in the body and in foods are divided 

into two groups : 

a. Non-nitrogenous, containing carbon, hydrogen, and 

oxygen only. 

b. Nitrogenous, containing carbon, hydrogen, oxygen, 

nitrogen, sulfur, and phosphorus. 

2. Non-nitrogenous compounds divided into two groups : 

a. Carbohydrates : 

Definition of a carbohydrate — examples* 
Forms less than 1 % of the body. Why then so im- 
portant a part of our diet ? 

b. Fats: 

Definition of a fat — example. 
Why so useful in our diet ? 



APPENDIX 147 

D. A Study of Some of the Important Carbohydrates of the Starch Group. 

1. Starch (C 6 Hi O 5 ) n : 

a. Vegetables and plants in which it is most abundant. 

b. How obtained commercially. 

c. Physical properties : 

Starch grains from different sources differ in size 
and shape (microscope). 

d. Chemical properties : 

Effect of gentle dry heat. 
Effect of intense heat without air. 
Effect of concentrated sulfuric acid. 
Products of combustion. 
Hydrolysis of starch. 

e. Manufacture of glucose from starch. 
/. The iodine test for starch. 

g. Foods containing much starch : 

See table in Appendix. 
h. Foods containing little starch : 

See table in Appendix. 
i. Foods containing no starch : 

See table in Appendix. 
j. Commercial uses of starch. 

2. Dextrin (C 6 Hi O 5 ) n : 

a. Prepared by heating starch from 210° C. to 280° C. 

b. Physical properties, yellow or white, sweet, sticky, 

soluble in water. 

c. Insoluble in alcohol. 

d. Intermediate product in the hydrolysis of starch. 

e. Effect on iodine solution (red, purple coloration). 
/. Effect on Fehling's solution. 

g. Use of dextrin. 

3. Glycogen : 

a. Found in the liver of animals. 

b. Soluble in cold water. 



148 APPENDIX 

c. Effect on iodine solution (reddish coloration). 

d. Use of glycogen to animal. 
4. Cellulose (CeHioOsJn : 

a. Where found : 

In nearly all plants, especially the stems, roots, and 

leaves. 
Commercial source is young tree trunks, cotton, 

hemp, flax, jute, ramie, coconut fiber. 

b. How obtained commercially. 

c. Physical properties : 

Seed fibers or last fibers. Colorless, odorless, taste- 
less, insoluble in water. 

d. Chemical properties : 

Dilute acids no effect. 

Dilute bases no effect. 

Iodine solution no effect. 

Fehling's solution no effect. 

Concentrated sulfuric acid forms a clear jelly-like 
mass called amyloid. Longer action forms dex- 
trin. Still longer dextrose. 

Strong sodium hydroxide makes cellulose fibers 
transparent and larger. (Mercerizes them.) 

Soluble in a concentrated solution of zinc chloride. 

Soluble in Sweitzer's reagent. 

Nitric and sulfuric acid changes it to nitrocellulose 
or guncotton. 

Nitrocellulose dissolved in ether and alcohol gives 
collodion. 

Nitrocellulose dissolved in ether and camphor gives 
celluloid. 

e. Commercial uses of cellulose. 
/. Uses as food. 

g. Foods containing much cellulose. 

h. Foods containing little or no cellulose. 



APPENDIX 149 

5. Gums : 

a. Where found. 

b. How obtained commercially. 

c. Physical properties : 

Effect of cold water, alcohol, ether. 

d. Chemical properties : 

Effect of iodine. 

Effect of Fehling's solution. 

Hydrolysis of gums. 

e. Use of gums in the preparation of foods. 
/. Commercial uses of gums. 

6. Pectin: 

a. Where found. 

b. Soluble in hot water. 

c. Physical properties. 

d. Precipitated by alcohol, acid, or sugar. 

e. Hydrolyzed by long boiling with acid. 
/. Fruits containing much pectin. 

E. Important Carbohydrates of the Sugar Group. 
1. Sucrose — cane sugar, C12H22O11 : 

a. Substances containing much — roots like beets and 

carrots, stems of grasses, corn stalks, sugar cane, 
sap of some trees, birch and maple. 

b. Commercial source — sugar cane, sugar beets. 

c. Preparation of sugar from cane. 

1. Extraction of juice. 

2. Separation of crystals — centrifugal. 

3. Clarifying. 

4. Evaporation. 

d. Preparation from beets. 

1. Wash and slice beets. 

2. Extraction of juice by diffusion cells (osmosis). 

3. Clarifying. 



150 APPENDIX 

4. Evaporation. 

5. Separation of crystals. 

e. Physical properties of sucrose. 

Color, odor, taste, form, solubility in hot and cold 
water. 
/. Chemical properties of sucrose. 

Gentle heat melts it. This, when cold, forms 
barley sugar: 

More intense heat changes it to caramel. 

Strong heat decomposes it. 

CaHjBOu+heat — >- 12 C + ll H 2 

Concentrated sulfuric acid decomposes it. 

CMHaAi + CHaSOJ — >- 12 C + ll H 2 

Will not reduce Fehling's solution. 

Boiled with a dilute acid it hydrolyzes. 

Ci2H 22 0n+H 2 (dilute acid) — >-C 6 H 12 6 +C 6 H 12 6 

sucrose dextrose levulose 

Not easily fermented until yeast hydrolyzes it and 

the simple sugars so formed undergo fermentation. 
Ci 2 H 22 0ii+H 2 — >- C6Hi 2 06+C6Hi 2 06 
C 6 H 12 6 +yeast — >- 2 C 2 H 5 OH+2 C0 2 

glucose alcohol carbon 

dioxide 

g. Use of sucrose as food. 
h. Commercial uses. 
2. Lactose — milk sugar, Ci 2 H 22 0n. 

a. Found in milk of all mammals. 

b. Prepared from whey. 

c. Physical properties of lactose. Color, odor, not so 

sweet as cane sugar, not so soluble in cold water as 
cane sugar or grape sugar, more soluble in hot 
water. 

d. Chemical properties of lactose. 

Heat melts it. 

Intense heat decomposes it. 



APPENDIX 151 

Sulfuric acid decomposes it. 

It will reduce Fehling's solution with ^ the power 

of dextrose. 
Dilute acids hydrolyze it. 
Ci2H 22 0ii+H 2 b (dilute acid) — ^C 6 H 12 6 + C 6 H 12 6 

lactose dextrose galactose 

It is easily fermented by yeast. 
e. Use of lactose. In the preparation of children's foods. 
In pharmacy in the preparation of pellets and 
tablets. 
Maltose — malt sugar, Ci 2 H 22 0n. 

a. Preparation. 

1. Malt diastase on starch. 

2. Dilute acids on starch. 

3. C6H 10 O 5 +H 2 O(diluteacid)— ^CeHioOs+C^H^On 

starch dextrin maltose 

b. Chemical properties. 

Heat melts it. 
Intense heat decomposes it. 

Reduces Fehling's solution with -J the power of dex- 
trose. 
Easily fermented. 
Dilute acids hydrolyze it. 
Ci 2 H 22 O n +H 2 (dilute acid) — >- C 6 H 12 6 +C 6 H 12 6 

maltose dextrose dextrose 

Dextrose-glucose — grape sugar, CeH^Oe. 

a. Dextrose, a white, crystalline solid. 
Glucose, a white thick sirup. 

Grape sugar, heavy brown-white lumps. Three 
names for the same sugar. The difference in 
physical properties is due to methods of purify- 
ing it. 

b. Substances containing much — grapes, apples, apri- 

cots, peaches, all fruits, especially dried fruits. 



152 APPENDIX 

c. Preparation. 

(1) Hydrolysis of sucrose. 

CiaHaOn+HaOCdUuteacid)— ^^BHiaOe+CeHiaOe 

sucrose dextrose levulose 

(2) Hydrolysis of lactose. 

Ci 2 H 22 O u +H 2 (dilute acid)— ^C G H 12 6 +C 6 H 12 6 

lactose dextrose galactose 

(3) Hydrolysis of maltose. 
C 12 H 2 20i 1 +H 2 (dilute acid) — >■ 2 C 6 H 12 6 

maltose dextrose 

(4) Hydrolysis of cellulose. 

2 C 6 H 10 O 5 +H 2 O (acid) — ^ C 6 H 10 O 5 +C 6 H 12 O 6 

cellulose dextrin dextrose 

(5) Hydrolysis of starch — this is the commercial 

method. 
C6H 1 o05+H 2 0(diluteacid)-^C 6 H 10 05 + Ci 2 H 22 11 

starch dextrose maltose 

Ci 2 H 22 O n +H 2 — ^ 2 C 6 H 12 6 

maltose dextrose 

or glucose 

If conversion is not complete, the product is 
glucose (mixture of dextrin, maltose, and dex- 
trose). 

If more complete, the product is grape sugar (dex- 
trose and maltose). 

If conversion is complete, the product is dextrose. 

d. Physical properties of dextrose. 

White, crystalline, odorless, f as sweet as sugar, 
soluble in cold water, more soluble in hot 
water. 

e. Chemical properties of dextrose. 

Moderate heat melts it. 
Intense heat decomposes it. 

C 6 H 12 6 — ^6C+6H 2 
Concentrated sulfuric acid decomposes it. 

C 6 H 12 6 — ^6C+6H 2 



APPENDIX 153 

Ferments with yeast dextrose. 

CeHiaOe+yeast >- 2 C 2 H 5 OH+2 C0 2 

alcohol carbon dioxide 
Reduces Fehling's solution. 
/. Uses of glucose. 

5. Levulose — fruit sugar, C 6 Hi 2 06 

a. Found in fruits with dextrose. 

b. Prepared by inversion of cane sugar. 
C12H22O11+H2O (dilute acid) — ^ C 6 H 12 6 +C 6 H 12 6 

sucrose dextrose levulose 

c. Properties similar to those of dextrose. 

6. Galactose from milk sugar. 

a. Prepared by hydrolysis of milk sugar. 
Ci 2 H 22 0n+H 2 — >- C6Hi 2 06+CeHi 2 06 

lactose gelactose dextrose 

b. Properties similar to those of dextrose. 

F. Fats and Oils. 

1. Chemical composition of fats. 

a. Fats are esters, i.e. organic salts. 

b. Base -f- acid — >- salt + water. 

c. Alcohol +acid — >- ester + water. 
C2H5OH+CH3COOH — ^ CH 3 COOC 2 H 5 +H 2 

Ethyl alcohol acetic acid ethylacetate 

d. Glycerin -(-acid — >- fat + water. 
C 3 H 5 (OH) 3 +3 C17H35COOH — >- 

glycerin stearic acid 

(C 17 H 3 5COO) 3 C3H5+3H 2 

stearin (a fat) 

C 3 H 6 (OH)8+3 C 15 H 31 COOH — *- 

glycerin palmitic acid 

(C 15 H 31 COO) 3 C 3 H 5 +3H 2 

palmitin (a fat) 

C 3 H 5 (OH) 3 +3 C 17 H 33 COOH — >- 

glycerin oleic acid 

(C 17 H 33 COO) 3 C 3 H 5 +3 H 2 

olein (an oil) 



154 APPENDIX 

e. Ordinary fats, such as lard and tallow, are mixtures of 
the esters palmitin and stearin chiefly, while oils, 
such as olive oil, cottonseed oil, sperm oil, con- 
tain more olein than palmitin and stearin. 

2. Occurrence of fats and oils. 

a. Animal origin. 

Milk (butter fat). 

Fatty tissue (lard, tallow, whale oil, sperm oil, and 

cod liver oil). 
Eggs (yolks). 

b. Plant origin. 

Seeds (sunflower, cotton, flax, castor bean, and cacao 

beans). 
Nuts (coconut, almond, peanut, pecans). 
Fruits (olive, avocado). 

3. Methods of obtaining fats and oils. 

a. Heat alone, called rendering (lard, tallow, and other 

animal fats and oils). 

b. Pressing without heat (olives, peanuts, cotton seeds, 

and castor beans), called expressing. 

c. Pressing with heat (cocoa beans, coconuts, al- 

monds). 

d. Extraction by means of ether, chloroform, carbon 

tetrachloride. 

4. Physical properties of fats. 

a. Fats are solids, oils are liquids. 

b. Characteristic odor and taste. 

c. Insoluble in water, soluble in gasoline, ether, and 

chloroform. 

d. With egg albumen, gum arabic, or other mucilage- 

like substances, oils and fats form emulsions. 

e. Rubbed on paper, oils form a translucent spot. 

This is the "grease spot" test for oils and 
fats. 



APPENDIX 155 

5. Chemical properties of fats. 

a. Intense heat decomposes fats, forming acrolein. 

b. Oils burn, forming carbon dioxide and water. 

c. When boiled with strong bases, fats are first hydrolyzed 

and then saponified, i.e. soaps are formed. When 
esters are hydrolyzed by means of sodium hy- 
droxide, the organic acid and the alcohol are 
formed. The acid then combines with the sodium 
hydroxide to form a salt thus : 

1. CH 3 COOC 2 H 5 +H 2 — ^ CH 3 COOH+C 2 H 5 OH 

ethyl acetate acetic acid ethyl alcohol 

(by NaOH) 

2. CH 3 COOH+NaOH — >■ CH 3 COONa+H 2 

acetic acid sodium sodium acetate 

hydroxide 

When fats are hydrolyzed by means of sodium 

hydroxide, the organic acid and the alcohol 

glycerin are formed. The acid then combines 

with the sodium hydroxide to form a soap, thus : 

1. (C 17 H 35 COO) 3 C 3 H 5 +3 H 2 (by NaOH) 

stearin (a fat) 

— >■ 3 C 17 H 35 COOH+C 3 H 5 (OH) 3 

stearic acid glycerin 

2. C 17 H 35 COOH+NaOH — ^ C 17 H 35 COONa+H 2 

stearic acid sodium sodium stearate 

hydroxide (a soap) 

6. Uses of fats as food. 

a. Give 2-J- times as much heat to the body as the carbo- 
hydrates. 

7. Commercial use of fats. 

a. For preserving meats and fish, for lubricants, for 
varnishes, paints, soaps, candles. 

Nitrogenous Substances or Proteins. 

1. Albumens — soluble in cold water, coagulated by heat. 

a. Where found (milk, egg, blood). 

b- Physical properties — solubility. 



156 APPENDIX 

c. Effect of heat, odor. 

d. Decomposed by soda lime gives ammonia. 

e. Xanthoproteic test. 
/. Millon's test. 

g. Use to body. 

2. Casein — soluble in cold and hot water. 

a. Where found (milk of all mammals). 

b. Precipitated by any acid. 

c. Coagulated by rennin. 

d. Effect of heat — odor. 

e. Xanthoproteic test. 
/. Millon's test. 

g. Decomposition test. 

3. Globulins — insoluble in hot or cold water. 
Gluten in wheat and other cereals. 

a. Physical properties — solubility. 

b. Effect of heat — odor. 

For other tests see 1 and 2 above. 
Myosin in meat. 
a. Effect of heat — odor. 

For other tests see 1 and 2 above. 
Legumen in peas and beans. 

For tests see 1 and 2 above. 

4. Albuminoids or gelatinoids — soluble in hot water, on 

long boiling. Form jellies on cooling. 
Collagen in cartilage, skins and bones. 

a. Will not give Xanthoproteic test. 

b. Will not give Millon's test. 

c. When heated — odor. 

d. Decomposition test. 

e. Used to make commercial gelatin. 

Keratin in hair, hoofs, nails, very insoluble, contains 

much sulfur, 
a. For chemical properties see collagen above. 



APPENDIX 157 

b. Contains more sulfur than other proteins. 

c. Used to make glue. 

d. No food value. 



DIGESTION OF FOODS 

Starch Group. 

1. Starch. 

In mouth, cooked starch changed to maltose and 

dextrose. 
In stomach, no change. 
In small intestine, cooked and uncooked starch completely 

changed to maltose and dextrose. 

2. Cellulose not digested. It is softened in small intestine. 

Sugar Group. 

1. Sucrose, lactose, maltose. 
In mouth, no change. 

In stomach, the acids present partly hydrolyze them to 

the simple sugars. 
In small intestine, completely hydrolyzed by the ferment 

invertin. 

2. Glucose, levulose, galactose. 

Ready for the blood without being changed. 

Fats. 

In the mouth, no action. 
In the stomach no action. 
In the small intestine : 

1. Some of the fats form emulsions with the proteins 

present. 

2. Steapsin splits fats into fatty acids and glycerin. 
C 3 H 5 (C 17 H35COO)3+3H 2 

stearin 

— >■ C 3 H 5 (OH) 3 +3 C 17 H 35 COOH 

glycerin stearic acid 



158 



APPENDIX 



3. Then the fatty acid plus the alkali present forms soaps. 
C 17 H 35 COOH+NaOH — ^ C 17 H 35 COONa+H 2 

fatty acid soap 

4. Fat and soaps form an emulsion. 

Digestion of Proteins. 

1. In mouth, no action. 

2. In stomach : 

Dissolved proteins coagulated by rennin and acid. 
All coagulated proteins changed to peptones by ferment 
pepsin aided by acids. 

3. In small intestine : 

All proteins changed to peptones by ferment trypsin. 

ACTION OF DIGESTIVE JUICES 



Name of Di- 
gestive 
Juice 


From 


Action in 


Alkaline 
or Acid 


Name of 
Ferment 


Action of Ferment 


Saliva 


Salivary 
gland 


Mouth 


Alkaline 


Ptyalin 


Cooked starch to 
maltose. Acts 
slowly on glycogen. 
No effect on cellu- 
lose or uncooked 
starch. 


Gastric 


Walls of 


Stomach 


Acid 


1. Acid 


1. Sucrose group of 


juice 


stom- 




(lactic 


alone 


sugars hydro- 




ach 




and 




lyzed to dextrose. 








hydro- 


2. Acid 


2. Coagulates 








chloric 


alone 


proteins. 








acids) 


3. Ren- 

nin 

4. Pep- 

sin 


3. Coagulates 

proteins. 

4. Proteins to pep- 

tones. Starch 
not changed in 
stomach. 



APPENDIX 



159 



Name of Di- 
gestive 
Juice 


From 


Action in 


Alkaline 
or Acid 


Name of 
Ferment 


Action of Ferment 


Pancreatic 


Pancreas 


Small 


Alkaline 


1. Amy- 


1. 


All starch to 


juice 




intes- 
tine 




lop- 
sin 

2. In- 

ver- 
ts 

3. Steap- 

sin 

4. Tryp- 

sin 


2, 

3. 

4. 


maltose. 

Sucrose, maltose, 
lactose to simple 
sugars. 

Splits fats into 
fatty acids and 
glycerin. 
Fatty acids 
plus alkalies 
form soap. 
Soap plus fat 
forms an emul- 
sion. Proteids 
plus fat form 
an emulsion. 

Proteins to 
peptones. 



TABLES SHOWING AVERAGE HEIGHT, WEIGHT, SKIN 
SURFACE, AND FOOD UNITS REQUIRED DAILY WITH 
VERY LIGHT EXERCISE 



Boys 



Age 


Weight in Pounds 


Calories or Food Units 


5 


41.09 


816.2 


6 


45.17 


855.9 


7 


49.07 


912.4 


8 


53.92 


981.1 


9 


59.23 


1043.7 


10 


65.30 


1117.5 


11 


70.18 


1178.2 


12 


76.92 


1254.8 


13 


84.85 


1352.6 


14 


94.91 


1471.3 



160 



APPENDIX 



TABLES SHOWING AVERAGE HEIGHT, WEIGHT, SKIN 
SURFACE, AND FOOD UNITS REQUIRED DAILY WITH 
VERY LIGHT EXERCISE {Continued) 

Girls 



Age 


Weight in Pounds 


Calories or Food Units 


5 


39.66 


784.5 


6 


43.28 


831.9 


7 


47.46 


881.7 


8 


52.04 


957.1 


9 


57.07 


1018.5 


10 


62.35 


1081.0 


11 


68.84 


1148.5 


12 


78.31 


1276.8 



Men 









Calories ob 


Food Units 




Height 


Weight in 
Pounds 










in Inches 














Proteids 


Fats 


Carbohydrates 


Total 


61 


131 


197 


591 


1182 


1970 


62 


133 


200 


600 


1200 


2000 


63 


136 


204 


612 


1224 


2040 


64 


140 


210 


630 


1260 


2100 


65 


143 


215 


645 


1290 


2150 


66 


147 


221 


663 


1326 


2210 


67 


152 


228 


684 


1368 


2280 


68 


157 


236 


708 


1416 


2360 


69 


162 


243 


729 


1458 


2430 


70 


167 


251 


753 


1506 


2510 


71 


173 


260 


780 


1560 


2600 


72 


179 


269 


807 


1614 


2690 


73 


185 


278 


834 


1768 


2780 


74 


192 


288 


864 


1728 


2880 


75 


200 


300 


900 


1800 


3000 



APPENDIX 
Women 



161 









Calories or Food Units 




Height 


Weight in 
Pounds 










in Inches 














Proteids 


Fats 


Carbohydrates 


Total 


59 


119 


179 


537 


1074 


1790 


60 


122 


183 


549 


1098 


1830 


61 


124 


186 


558 


1116 


1860 


62 


127 


191 


573 


1146 


1910 


63 


131 


197 


591 


1182 


1970 


64 


134 


201 


603 


1206 


2010 


65 


139 


209 


627 


1254 


2090 


66 


143 


215 


645 


1290 


2150 


67 


147 


221 


663 


1326 


2210 


68 


151 


227 


681 


1362 


2270 


69 


155 


232 


696 


1392 


2320 


70 


159 


239 


717 


1434 


2390 



Note. — With active exercise an increase of about 20 per cent total 
food units may be needed. 



TABLE OF 100 FOOD UNITS 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 






Beef, round, boiled (fat) 
Beef, round, boiled 

(lean) 

Beef, round, boiled 

(med.) 

Beef, 5th rib, roasted 
Beef, 5th rib, roasted 
Beef, 5th rib, roasted 
Beef, ribs, boiled . . 



Cooked Meats 
Small serving 

Large serving 

Small serving 
Half serving . . 
Small serving 
Very small serving 
Small serving 



36 


1.3 


40 


60 


62 


2.2 


90 


10 


44 


1.6 


60 


40 


18.5 


.65 


12 


88 


32 


1.2 


25 


75 


25 


.88 


18 


82 


30 


1.1 


27 


73 



00 

00 

00 
00 
00 
00 
00 



162 


APPENDIX 












TABLE OF 100 FOOD UNITS ( 


Continued) 










Wt. of 100 
Calories 


Per Cent 


OF 




"Portion" Con- 
taining 100 Food 












Name of Food 














Units (Approx.) 


go 

s 

c3 


1 

c 

3 


-a 
o 


ta 


c3 s. 






6 


o 


£ 


fa 


O-d 


Cooked Meats (Continued) 






Beef, ribs, boiled . . 


Very small serving 


25 


.87 


21 


79 


00 


Chicken, canned . . 


One thin slice 


27 


.96 


23 


77 


00 


Lamb chops, boiled, av. 


One small chop . 


27 


.96 


24 


76 


00 


Lamb, leg, roasted 


Ord. serving . . 


50 


1.8 


40 


60 


00 


Mutton, leg, boiled . 


Large serving 


34 


1.2 


35 


65 


00 


Pork, ham, boiled (fat) 


Small serving 


20.5 


.73 


14 


86 


00 


Pork, ham, boiled . . 


Ord. serving . . 


32.5 


1.1 


28 


72 


00 


Pork, ham, roasted (fat) 


Small serving 


27 


.96 


19 


81 


00 


Pork, ham, roasted 














(lean) 


Small serving 


34 


1.2 


33 


67 


00 


Turkey, as pur., canned 


Small serving 


28 


.99 


23 


77 


00 


Veal, leg, boiled . . 


Large serving 


67.5 


2.4 


73 


27 


00 


Uncooked Meats, Edibi 


,e Portion 






Beef, loin, av. (lean) 


Ord. serving . . 


50 


1.8 


40 


60 


00 


Beef, loin, av. (fat) 


Small serving 


30 


1.1 


22 


78 


00 


Beef, loin, porterhouse 














steak, av 


Small steak . . 


36 


1.3 


32 


68 


00 


Beef, loin, sirloin steak, 














av 


Small steak . . 


40 


1.4 


31 


69 


00 


Beef, ribs, lean, av. . 


Ord. serving . . 


52 


1.8 


42 


58 


00 


Beef, round, lean, av. 


Ord. serving . . 


63 


2.2 


54 


46 


00 


Beef, tongue, av. . . 


Ord. serving . . 


62 


2.2 


47 


53 


00 


Chicken (broilers), av. 


Large serving 


90 


3.2 


79 


21 


00 


Clams, round in shell, 














av 


Twelve to 16 . . 


210 


7.4 


56 


8 


36 


Cod, whole .... 


Two servings . . 


138 


4.9 


95 


5 


00 


Goose (young), av. 


Half serving . . 


25 


.88 


16 


84 


00 


Halibut steaks, av. 


Ord. serving . . 


81 


2.8 


61 


39 


00 


Liver (veal), av. . . 


Two small serv- 














ings .... 


79 


2.8 


61 


39 


00 


Lobster, whole, av. 


Two servings 


117 


4.1 


78 


20 


2 


Mackerel (Span.), 














whole, av 


Ord. serving . . 


57 


2 


50 


50 


00 



APPENDIX 



163 



Name of Food 



"Portion " Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent cf 



Uncooked Meats, Edible Portion {Continued) 



Mutton leg, hind, lean, 
av 

Oysters, in shell, av. . 

Pork, loin chops, av. . 

Pork, ham, lean, av. . 

Pork, bacon, med. fat, 
av 

Salmon (Cal.), av. . . 

Shad, whole, av. . . 

Trout, brook, whole, 
av 



Turkey, av. 



Artichokes, av., canned 
Asparagus, av., canned 
Asparagus, av., cooked 
Beans, baked, canned 
Beans, Lima, canned . 
Beans, string, cooked . 
Beets, edible portion, 

cooked 

Cabbage, edible por- 
tion 

Carrots, edible portion, 

fresh 

Carrots, cooked . . 
Cauliflower, as pur- 
chased 

Celery, edible portion 
Corn, sweet, cooked . 
Cucumbers, edible por- 
tion 



Ord. serving . . 
One dozen . . . 
Very small serving 
Small serving 

Small serving 
Small serving 
Ord. serving . . 

Two small serv- 
ings .... 
Two small serv- 



ings 



Vegetables 



Small side dish 
Large side dish 
Five servings . 

Three servings 



Two servings 



One side dish 



50 


1.8 


41 


59 


193 


6.8 


49 


22 


27 


.97 


18 


82 


36 


1.3 


29 


71 


15 


.53 


6 


94 


42 


1.5 


30 


70 


60 


2.1 


46 


54 


100 


3.6 


80 


20 


33 


1.2 


29 


71 



430 


15 


14 





540 


19 


33 


5 


206 


7.19 


18 


63 


75 


2.66 


21 


18 


126 


4.44 


21 


4 


480 


16.66 


15 


48 


245 


8.7 


2 


23 


310 


11 


20 


8 


215 


7.6 


10 


8 


164 


5.81 


10 


34 


312 


11 


23 


15 


540 


19 


24 


5 


99 


3.5 


13 


10 


565 


20 


18 


10 



164 



APPENDIX 



TABLE OF 100 FOOD UNITS {Continued) 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. op 100 

Calories 



Per Cent of 



Vegetables {Continued) 



Egg plant, edible por- 
tion 

Lettuce, edible portion 

Mushrooms, as pur- 
chased 

Onions, fresh, edible 
portion 

Onions, cooked . . . 

Parsnips, edible portion 
Parsnips, cooked . 
Peas, green, canned 
Peas, green, cooked 
Potatoes, baked 
Potatoes, boiled 
Potatoes, mashed 

(creamed) . . . 
Potatoes, steamed . 
Potatoes, chips . . 
Potatoes, sweet, cooked 
Pumpkins, edible por- 
tion 

Radishes, as purchased 
Rhubarb, edible por- 
tion 

Spinach, cooked . . 
Squash, edible portion 
Succotash, canned . . 
Tomatoes, fresh as 
purchased .... 
Tomatoes, canned . . 
Turnips, edible portion 
Vegetable oysters . . 



Two large serv 

ings . . . 
1| servings 

Two servings . 
One serving . 
One good sized 
One large sized 

One serving . 
One serving . 
One half serving 
Half av. potato 



Two ord. servings 
Ord. serving . . 
Four av. . . . 
Two large servings 



350 


12 


17 


10 


505 


18 


25 


14 


215 


7.6 


31 


8 


200 


7.1 


13 


5 


240 


8.4 


12 


40 


152 


5.3 


10 


7 


163 


5.84 


10 


34 


178 


6.3 


25 


3 


85 


3 


23 


27 


86 


3.05 


11 


1 


102 


3.62 


11 


1 


89 


3.14 


10 


25 


101 


3.57 


11 


1 


17 


.6 


4 


63 


49 


1.7 


6 


9 


380 


13 


15 


4 


480 


17 


18 


3 


430 


15 


10 


27 


174 


6.1 


15 


66 


210 


7.4 


12 


10 


100 


3.5 


15 


9 


430 


15 


15 


16 


431 


15.2 


21 


7 


246 


8.7 


13 


4 


273 


9.62 


10 


51 



APPENDIX 



165 



Name of Food 



"Portion " Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 



Apples, as purchased . 
Apricots as purchased 
Dates, edible portion . 
Dates, as purchased . 
Figs, edible portion 
Prunes, edible portion 
Prunes, as purchased . 
Raisins, edible portion 
Raisins, as purchased . 



Fruits (Dried) 



Three large 

One large . 
Three large 



34 


1.2 


3 


7 


35 


1.24 


7 


3 


28 


.99 


2 


7 


31 


1.1 


2 


7 


31 


1.1 


5 





32 


1.14 


3 





38 


1.35 


3 





28 


1 


3 


9 


31 


1.1 


3 


9 



Fruits (Fresh or Cooked) 



Apples, as purchased . 

Apples, baked . . . 

Apples, sauce . . . 

Apricots, edible portion 

Apricots, cooked . . 

Bananas, edible portion 

Blackberries .... 

Cantaloupe .... 

Cherries, edible portion 

Cranberries, as pur- 
chased 

Grapes, as purchased, 
av. . . 

Grape fruit 

Grape juice 

Lemons 

Lemon juice 

Nectarines 

Olives, ripe 

Oranges, as purchased 
av 

Oranges, juice . . 

Peaches, as purchased, 




Two apples . , 

Ord. serving . , 

Large serving 
One large . . , 

Half ord. serving 



Small glass 



About seven . 

One very large 
Large glass 

Three ordinary 



206 


7.3 


3 


7 


94 


3.3 


2 


5 


111 


3.9 


2 


5 


168 


5.92 


8 





131 


4.61 


6 





100 


3.5 


5 


5 


170 


5.9 


9 


16 


243 


8.6 


6 





124 


4.4 


5 


10 


210 


7.5 


3 


12 


136 


4.8 


5 


15 


215 


7.57 


7 


4 


120 


4.2 








215 


7.57 


9 


4 


246 


8.77 








147 


5.18 


4 





37 


1.31 


2 


91 


270 


9.4 


6 


3 


188 


6.62 








290 


10 


7 


2 



166 



APPENDIX 



TABLE OF 100 FOOD UNITS {Continued) 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 



Fruits 


(Fresh or Cooked) {Continued) 






Peaches, sauce . . . 


Ord. serving . . 


136 


4.78 


4 


2 


94 


Peaches, juice . . . 


Ord. glass . . . 


136 


4.80 








100 


Pears ...... 


One large pear . 


173 


5.40 


4 


7 


89 


Pears, sauce .... 




113 


3.98 


3 


4 


93 


Pineapples, edible por- 














tion, av 




226 


8 


4 


6 


90 


Raspberries, black . . 




146 


5.18 


10 


14 


76 


Raspberries, red . . 




178 


6.29 


8 





92 


Strawberries, av. . . 


Two servings . . 


260 


9.1 


10 


15 


75 


Watermelon, av. . . 




760 


27 


6 


6 


88 




Dairy Products 








Butter 


Ordinary pat . . 


12.5 


.44 


.5 


99.5 


00 


Buttermilk .... 


1§ glasses . 




275 


9.7 


34 


12 


54 


Cheese, Am., pale . . 


1\ cu. in. . 




22 


.77 


25 


73 


2 


Cheese, cottage . . . 


Four cu. in 




89 


•3.12 


76 


8 


16 


Cheese, full cream . . 


1^ cu. in. . 




23 


.82 


25 


73 


2 


Cheese, Neufchatel 


\\ cu. in. . 




29.5 


1.05 


22 


76 


2 


Cheese, Swiss . . . 


1| cu. in. . . 




23 


.8 


25 


74 


1 


Cheese, pineapple . . 


If cu. in. . 




20 


.72 


25 


73 


2 


Cream 


\ ord. glass 




49 


1.7 


5 


86 


9 


Milk, condensed, 














sweetened .... 




30 


1.06 


10 


23 


67 


Milk, condensed, 














unsweetened . . . 




59 


2.05 


24 


50 


26 


Milk, skimmed . . . 


1| glasses . . . 


255 


9.4 


37 


7 


56 


Milk, whole .... 


Small glass 




140 


4.9 


19 


52 


29 



Cakes, Pastry, Puddings, and Desserts 



Cake, chocolate layer . 


Half ord. sq. pc. 


28 


.98 


7 


22 


71 


Cake, gingerbread . . 


Half ord. sq. pc. 


27 


.96 


6 


23 


71 


Cake, sponge . . . 


Small piece . . 


25 


.89 


7 


25 


68 


Custard, caramel . 




71 


2.51 


19 


10 


71 



APPENDIX 



167 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 



Cakes, Pastry, Puddings, and Desserts {Continued) 



Custard, milk . 
Custard, tapioca 
Doughnuts . 
Lady fingers . 
Macaroons . 
Pie, apple 
Pie, cream 
Pie, custard . 
Pie, lemon 
Pie, mince 
Pie, squash . 
Pudding, apple sago 
Pudding, brown betty 
Pudding, cream rice . 
Pudding, Indian meal 
Pudding, apple tapioca 
Tapioca, cooked . . 



Catsup, tomato, av. . 

Candy, plain . . . 

Candy, chocolate . . 

Honey 

Marmalade, orange 

Molasses, cane . . . 

Olives, green, edible 
portion 

Olives, ripe, edible por- 
tion 

Pickles, mixed . . . 

Sugar, granulated . . 



Sugar, maple 
Sirup, maple 



Ordinary cup 

f ordinary . 

§ doughnut 

Two 

Four 

\ piece 

\ piece 

| piece 

| piece 

\ piece 

-j piece 



\ ord. serving 
Very small serving 
\ ord. serving 
Small serving 
Ordinary serving 



Sweets and Pickles 



Four teaspoons 

Five to seven 
Five to seven 

Three heaping tea- 
spoons or I2 
lumps . . . 

Four teaspoons . 

Four teaspoons . 



122 


4.29 


26 


56 


69.5 


2.45 


9 


12 


23 


.8 


6 


45 


27 


.95 


10 


12 


23 


.82 


6 


33 


38 


1.3 


5 


32 


30 


1.1 


5 


32 


55 


1.9 


9 


32 


38 


1.35 


6 


36 


35 


1.2 


8 


38 


55 


1.9 


10 


42 


81 


3.02 


6 


3 


56.6 


2 


7 


12 


75 


2.65 


8 


13 


56.6 


2 


12 


25 


79 


2.8 


1 


1 


108 


3.85 


1 


1 



170 


6 


10 


3 


26 


.9 








30 


1.1 


1 


4 


30 


1.05 


1 





28.3 


1 


.5 


2.5 


35 


1.2 


.5 





32 


1.1 


1 


84 


38 


1.3 


2 


91 


415 


14.6 


18 


15 


24 


.86 








29 


1.03 








35 


1.2 









100 
100 
100 



168 APPENDIX 

TABLE OF 100 FOOD UNITS {Continued) 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 



Almonds, av. . . 
Brazil nuts . . . 
Chestnuts, fresh, av. 
Filberts, av. . . . 
Peanuts, av. . . . 
Pecans, polished 
Pine nuts (pignolias) 
Walnuts, California 



Bread, brown, av. . . 

Bread, corn (johnny- 
cake), av 

Bread, white, home 
made 

Cookies, sugar . . . 

Corn flakes, toasted . 

Corn meal, granular, 
av 

Corn meal, unbolted, 
av 

Crackers, graham 

Crackers, oatmeal 

Crackers, soda . 

Hominy, cooked 

Macaroni, av. . 

Macaroni, cooked 

Oatmeal, boiled 

Popcorn . . . 

Popcorn, uncooked 

Rice, boiled . . 

Rice, flakes . . 



Nuts (Edible Portion) 

Eight to fifteen 
Three ordinary size 

Ten nuts . . 
Thirteen double 
About eight . 
About eight . 
About six . . 

Cereals 



Ord. thick slice 
Small square . . 

Ord. thick slice . 

Two .... 

Ord. cereal dish 
full .... 

2\ level table- 
spoons . . . 

Three tablespoons 
Two .... 
Two .... 
3£ "Uneedas" . 
Large serving 

Ord. serving . . 
\\ servings . . 



Ord. cereal dish 
Ord. cereal dish 





15 


.53 


13 


77 


e 


14 


.49 


10 


86 




40 


1.4 


10 


20 




14 


.48 


9 


84 




18 


.62 


20 


63 




13 


.46 


6 


87 




16 


.56 


22 


74 




14 


.48 


10 


83 



43 


1.5 


9 


7 


38 


1.3 


12 


16 


38 


1.3 


13 


6 


24 


.83 


7 


22 


27 


.97 


11 


1 


27 


.96 


10 


5 


26 


.92 


9 


11 


23 


.82 


9.5 


20.5 


23 


.81 


11 


24 


24 


.83 


9.4 


20 


120 


4.2 


11 


2 


27 


.96 


15 


2 


110 


3.85 


14 


15 


159 


5.6 


18 




24 


.86 


11 


11 


28 


.98 


9 




87 


3.1 


10 




27 


.94 


8 





APPENDIX 



169 



Name of Food 



"Portion" Con- 
taining 100 Food 
Units (Approx.) 



Wt. of 100 
Calories 



Per Cent of 



Rolls, Vienna, av. . . 

Shredded wheat . . 

Spaghetti, av. . . . 

Wafers, vanilla . . . 

Wheat, flour, entire 
wheat, av. . . . 

Wheat, flour, graham 

Wheat, flour, patent, 
family, and straight 
grade spring wheat 

Zweiback 



Eggs, hen's, boiled . 
Eggs, hen's, whites 
Eggs, hen's, yolks . 
Omelet .... 
Soup, beef, av. . . 
Soup, bean, av. . . 
Soup, cream of celery 
Consomme . . . 
Clam chowder . . 
Chocolate, bitter . 

Cocoa 

Ice cream (Phila.) . 
Ice cream (N. Y.) . 



Cereals {Continued) 

One large . . . 
One biscuit . . 

Four .... 

Four tablespoons 
4^ tablespoons 



Four tablespoons 

Size thick slice of 

bread . . . 

Miscellaneous 

One large egg 
Of six eggs 
Two yolks 



Very large plate 
Two plates 

Two plates 
Half a square 

Half serving . 
Half serving . 



35 


1.2 


12 


7 


27 


.94 


13 


4.5 


28 


.97 


12 


1 


24 


.84 


8 


13 


27 


.96 


15 


5 


27 


.96 


15 


5 


27 


.97 


12 


3 


23 


.81 


9 


21 



59 


2.1 


32 


68 


181 


6.4 


100 





27 


.94 


17 


83 


94 


3.3 


34 


60 


380 


13 


69 


14 


150 


5.4 


20 


20 


180 


6.3 


16 


47 


830 


29 


85 


00 


230 


8.25 


17 


18 


16 


.56 


8 


72 


20 


.69 


17 


53 


45 


1.6 


5 


57 


48 


1.7 


7 


47 



81 
82.5 
87 
79 

80 
80 



85 
70 



00 
00 
00 
6 
17 
60 
37 
15 
65 
20 
30 
38 
46 



SPECIAL SOLUTIONS 

1. Cleaning Solution : 

Dissolve 25 grams of commercial sodium dichromate in 
150 cc. of water, then add 100 cc. of concentrated commercial 
sulfuric acid. The solution can be used repeatedly. 



170 APPENDIX 

2. Fehling's Solution : 

No. 1. Dissolve 34.64 grams of copper sulfate in 500 cc. of 
distilled water. 

No. 2. Dissolve 173 grams of Rochelle salts and 50 grams 
of sodium hydroxide in 500 cc. of water. Keep the two solutions 
in separate bottles. Mix equal parts just before using. The 
mixture must be alkaline. (For glucose test.) 

3. Haine's Solution : 

Dissolve 10 grams of CuSC>4 • 5 H 2 in 875 cc. of water and 
add 45 grams of KOH sticks. Add 100 cc. of glycerin. This 
is a single solution reagent and will keep for a year. (Test for 
glucose.) 

4. Halphen's Reagent : 

Dissolve 1 gram of sulfur in 100 cc. of carbon disulfide and 
then add 100 cc. of amyl alcohol. (Test for cottonseed oil.) 

5. Iodine (Tincture) : 

Dissolve 7 grams of iodine and 5 grams of potassium iodide in 
100 cc. of 95 % alcohol. 

6. Iodine (Starch Test) : 

5 grams iodine and 10 grams potassium iodide in 250 cc. of water 
(starch test). 

7. Ink Eradicator : 

No. 1. Tartaric acid, 20 grams dissolved in 100 grams of 
water. 

No. 2. Boil 5 grams of chlorinated lime in 100 cc. of water 
until pink color appears. Filter and add enough water to make 
up to 100 cc. Apply No. 1, absorb excess with blotter, and then 
apply No. 2. Sponge with ammonia, if used on clothing. Do 
not use on wool or silk. The following solutions may be used : 
No. 1. 8 grams of citric acid, 50 cc. of water, and 12 cc. of a satu- 
rated solution of borax. No. 2. Boil 18 grams of chlorinated 



APPENDIX 171 

lime in 60 cc. of water ; filter and add 12 cc. of a saturated sol. 
of borax. Use as in the first case. Not for wool or silk. 

8. Javelle Water : 

Dissolve 120 grams of sodium carbonate in 250 cc. of water. 
Stir 30 grams of chlorinated lime into 250 cc. of hot water. 
Mix the two solutions and decant the clear liquid for use as 
Javelle water. 

9. Litmus Solution Indicator : 

Powdered litmus should first be heated in alcohol to the boiling 
point. Filter the undissolved solid from the liquid and allow 
it to remain for several hours in cold water to remove alkaline 
impurities. Finally boil the solid residue with about 5 times 
its weight of water to make the solution for use. Preserve the 
solution by adding a little chloroform. 

10. Logwood Solution : 

Boil logwood chips in water till the solution is dark in color. 
Filter. It must be freshly prepared. 

11. Low's Reagent : 

Mix 4 volumes of glacial acetic acid with 1 volume of con- 
centrated sulfuric acid. 

12. Loewe's Reagent : 

Dissolve 35 grams of copper sulfate in 250 cc. of water, and 
add 12 cc. of glycerin. Add enough sodium hydroxide to dis- 
solve the precipitate that is formed when the hydroxide is first 
added. 

13. Millon's Reagent : 

Dissolve mercury in twice its weight of concentrated nitric 
acid. Dilute with an equal volume of cold water. Decant 
the clear liquid. 

14. Methyl Orange Indicator : 

Mix 0.4 gram of methyl orange powder with 30 cc. of 95 % 
ethyl alcohol and 170 cc. of water. 



172 APPENDIX 

15. Nessler's Solution : 

To 50 grams of potassium iodide in distilled water add satur- 
ated solution of mercuric chloride to red precipitation. Add 
350 cc. of a 50 per cent potassium hydroxide solution. Make 
up to one liter and allow to settle. 

16. Nickel Hydroxide Solution : 

Dissolve 5 grams of nickel sulfate in 100 cc. of water and 
add a solution of NaOH until all the nickel is precipitated as 
hydroxide. Wash it well and dissolve it in 25 cc. of concen- 
trated NH 4 OH and 25 cc. of water. This solution dissolves silk 
at once, and reduces the weight of vegetable fibers only \% 
and of wool only \ %. 

17. Phenolphthalein Indicator : 

Dissolve 0.4 gram of phenolphthalein in 120 cc. of 95 % ethyl 
alcohol and add 80 cc. of distilled water. 

18. Potassium Hydroxide in Alcohol : 

10 grams stick KOH dissolved in 100 grams of alcohol. 

19. Potassium Permanganate, Alkaline : 

KOH, 200 grams ; KMn0 4 , 8 grams ; distilled water, 1250 cc. 
Boil down to 1 liter. 

20. Standard Soap Solution : 

10 grams of white castile soap dissolved in 1 liter of dilute 
alcohol (one third water). Filter if not clear. 

21. Sulphanilic Acid : 

1 gram of solid in 100 cc. of hot distilled water. 

22. Sweitzer's Solution : 

Slowly add CuS0 4 solution to NaOH solution to precipitation. 
Filter. Dissolve the residue in NH 4 OH. Freshly prepared, 
it should dissolve cotton immediately. 

23. Wood Stain, Acid Proof : 

I. Dissolve 125 grams each of CuS0 4 and KCIO3 in the same 
liter of water. 



APPENDIX 173 

II. 150 grams of anilin oil mixed with 180 grams concentrated 
HC1 and a liter of water. 

Apply 2 coats of the boiling hot solution I with a brush. 
Allow each coat to dry. Apply 2 coats of solution II in the 
same manner. When the wood is dry, wash with hot soap- 
suds. Finish with raw linseed oil or hot liquid paraffin, and 
refinish with paraffin when the tables become dingy. 

24. Cobalt Chloride Test Paper: 

Dissolve 20 grams of CoCl 2 • 6 H 2 in about 200 cc. of 
water. Wet filter paper with the solution and dry it. Cutt 
into strips. Dry it over a flame before using it. Be careful 
in drying not to scorch the paper. 

25. Acid Mercuric Nitrate : 

Dissolve metallic mercury in twice its weight of concen- 
trated HN0 3 (sp. gr. 1.42) and dilute with twenty -five times 
its volume of water. 



